Displaying 1-10 letters out of 633 published
Under-representation of Frail or Medically Compromised Hypertensive Older People in the Paper
Under-representation of Frail or Medically Compromised Hypertensive Older People in the Paper Gulistan Bahat*, Asli Tufan, Mehmet Akif Karan
Department of Internal Medicine, Division of Geriatrics, Istanbul Medical School, Istanbul University, Capa, 34390, Istanbul, Turkey
Last name of authors: Bahat, Tufan, Karan
Corresponding author: Gulistan Bahat Address: Istanbul University, Istanbul Medical School, Department of Internal Medicine, Capa, 34390, Istanbul, Turkey Telephone: + 90 212 414 20 00-33204 Fax: + 90 212 532 42 08 E-mail address: email@example.com
We have read the article by Briasoulis et al. on effect of antihypertensive treatment in patients over 65 years of age with great interest . They comprehensively reviewed prospective randomized trials and assessed the effects of antihypertensive treatment on cardiovascular, all-cause mortality, stroke and heart failure in patients over 65 years of age.By the way of 18 clinically relevant studies, they concluded that treatment to blood pressure target of 150/80 mm Hg or to blood pressure reduction of >25/10 mm Hg effectively decreases all-cause mortality, cardiovascular mortality, stroke and heart failure in patients over 65 years of age.
However, elderly constitute a rather heterogeneous population and study recommendations could only be generalized to a given population if the given study participants are real and good representative of the population they recommend for. Departures from representativeness are amplified with increasing age. Progressively older adults who do participate in studies, may be progressively less representative of the group they are intended to reflect -as more non-representatively vigorous and robust. Consequently, the older the age, the greater the disparity may be between what is recommended based on 'evidence' and what is best for the patient .
The randomized trials that showed benefit from the treatment of hypertension in older adults included relatively fit patients . Accordingly, older adults who are frail may not benefit from antihypertensive therapy. There are some recent reports pointing out this problem. In a study of 2340 adults >65 years in 2012, among frail adults, there was no association between blood pressure and mortality. Moreover, a higher blood pressure was associated with a lower risk of death among the most frail (ie, those who could not walk the distance at all) . Another exampe is that, in a study of 1562 Latino adults aged 60 -101 years, the relationship between systolic blood pressure and mortality was reported to vary by self-reported walking speed. Higher systolic blood pressure was associated with an elevated risk of mortality in fast walkers while not in slow walkers .
We conclude that Briasoulis et al.'s conclusion could not be generalized to the elderly >65 years of age due to under-representation of frail or medically compromised patients that are rather prevalent in this age group . We think that their conclusion should be considered in view of this important limitation.
References 1. Cardiac risk factors and prevention: Effects of antihypertensive treatment in patients over 65 years of age: a meta-analysis of randomised controlled studies. Briasoulis A, Agarwal V, Tousoulis D, Stefanadis C. Heart 2014;100:317-323. 2. Golomb BA, Chan VT, Evans MA, Koperski S, White HL, Criqui MH. The older the better: are elderly study participants more non-representative? A cross-sectional analysis of clinical trial and observational study samples. BMJ Open. 2012;2:pii e000833. 3. Egan BM. Section Editors: Bakris GL, Kaplan NM, Schmader KE. Treatment of hypertension in the elderly patient, particularly isolated systolic hypertension. http://www.uptodate.com/contents/treatment-of-hypertension-in-the-elderly- patient-particularly-isolated-systolic- hypertension?source=search_result&search=hypertension+elderly&selectedTitle=1%7E150#H14493503 (accessed on March 6, 2014). 4. Odden MC, Peralta CA, Haan MN, Covinsky KE. Rethinking the association of high blood pressure with mortality in elderly adults: the impact of frailty. Arch Intern Med 2012; 172:1162. 5. Odden MC, Covinsky KE, Neuhaus JM, Mayeda ER, Peralta CA, Haan MN. The association of blood pressure and mortality differs by self-reported walking speed in older Latinos. J Gerontol A Biol Sci Med Sci. 2012;67:977 -83.
Conflict of Interest:
Ultrasound cardiac calcium assessment.
We read with interest, and we congratulate the authors for it, the nice paper by Kalsch et al, which demonstrates that aortic valve calcification (AVC) by computed tomography (CT), builds on Framingham score for risk stratification of future cardiovascular events. These are important data for preventive strategies, obtained in a wide and prospective study of healthy asymptomatics. In the discussion, the authors state that "Detection of degenerative aortic valve disease by assessing the prevalence of AVC can easily be performed by echocardiography" and that both echo and CT "provide a high degree of accuracy and reproducibility of AVC, with a higher degree of sensitivity provided by echocardiography but with less specificity than cardiac CT.". This difference can be understood in light of the known inability of ultrasound to differentiate between severe fibrosis and calcification, which inflates sensitivity but increases false-positive rate as long as calcium is the only endpoint; we want to stress that this "limitation" might also represent an advantage of ultrasound compared to CT, since fibrosis may also represent a marker of disease which is worth to detect. In a very recent paper from our group, too recent to be cited in the current paper, entitled "Aortic valve sclerosis as a marker of coronary artery atherosclerosis; a multicenter study of a large population with a low prevalence of coronary artery disease", Rossi A et al demontrated that the presence of AV sclerosis/calcification at echocardiography gives a patient 20 times (OR 21.8, 95CI 6.6-71.9, p <0.0001) the probability of angiographically obstructive CAD (in patients undergoing diagnostic coronary angiography before mitral surgery) after correction for the most relevant clinical factors. These data add to a wealth of literature demonstrating relevant value of heart valve sclerosis/calcification at ultrasound to predict coronary disease or coronary calcium or cardiovascular events, as also seen in prospective studies, such as the cardiovascular health or MESA study. CT has been fundamental to demonstrate the highly predictive value of coronary calcium and then that cardiac valve calcifications do relate to coronary calcium, also predicting cardiovascular events incrementally to Framingham score. Now it's time to prospectively test echocardiography, an incredibly easy, low-cost and radiation-free method, to investigate the potential of ultrasound cardiac calcium to risk-reclassify asymptomatic subjects. Thanks
Nicola Gaibazzi Andrea Rossi Pompilio Faggiano
Conflict of Interest:
Bicuspid aortopathy: searching for the answer in "non- progressors"
Evaldas Girdauskas1, Michael A. Borger2
1- Department of Cardiac Surgery, Central Hospital Bad Berka, Germany 2- Department of Cardiac Surgery, Heart Center Leipzig, University Leipzig, Germany
Keywords: bicuspid aortic valve, aortic aneurysm, aortopathy
Corresponding author: Evaldas Girdauskas, MD, PhD (Address: Department of Cardiac Surgery, Central Hospital Bad Berka, Robert-Koch- Allee 9, 99437 Bad Berka, Germany. Tel.: +49 3645851101; Fax: +49 3645853510 E-mail address: firstname.lastname@example.org)
We read with a great interest the manuscript by Detaint and co- authors published in the last issue of Heart . The authors should be congratulated for their efforts to shine some light on the controversial issue of bicuspid aortic valve (BAV)-associated aorthopathy in their current longitudinal echocardiographic study. Indeed, there are some novel and intriguing findings in this manuscript which may deserve a more extensive commentary.
The authors were able to demonstrate the fastest aortic dilatation rate at the ascending aortic level and smaller baseline aortic diameter being predictor of rapid aortic progression. Importantly, no correlation was found between aortic dilatation rate and BAV morphology as well as basic aortic phenotype. Typical morphology of BAV (i.e., L-R BAV fusion pattern) was independently associated with the baseline dilatation of the entire aortic root, which may reflect specific patterns of transvalvular flow in this BAV subtype .
The BAV population analyzed in this study is quite distinct from the "typical" surgical BAV population and these differences should be highlighted. First of all, 113/353 (32%) BAV patients without raphe were identified in the current study. In our experience, it is rather rare to find a BAV without raphe during aortic valve replacement (AVR) surgery. Similarly, BAV without raphe was identified in only 7% patients in the surgical series by Sievers and co-authors . Another major difference is the low proportion of patients with a BAV stenosis in the study (i.e., 14% of the study population). Calcific stenosis is the most common fate of congenital BAV (i.e., accounts for up 85% of surgically treated patients ) which is clearly underrepresented in the current series. As opposed to this, the authors revealed significant (i.e., at least moderate) BAV insufficiency in 123/353 (35%) study patients. Therefore, BAV cohort analyzed in this manuscript may represent a specific referral pattern of the tertiary care center. How many patients underwent AVR surgery during study period? Were these patients excluded from further echocardiographic follow-up? Is there any role of the variable "AVR surgery" in the progression of aortic diameters?
Was there a subgroup of BAV patients with the maximal progression of aortic diameters at the level of the sinuses of Valsalva? There is some evidence in the literature that patients with so-called "root phenotype" (i.e., Valsalva sinuses > ascending aorta) may represent a predominantly congenital form of BAV disease which is associated with a higher risk of adverse aortic events . What was the proportion of BAV patients in the subgroup of "sinuses phenotype" which showed stable aortic diameters at follow-up echocardiography?
However, the most intriguing question from this manuscript - why did aortic diameters remain stable in nearly half of the BAV patients? Is this only a function of limited echocardiographic follow-up interval (i.e., aortopathy would progress over longer follow-up periods) or a real phenotypic difference in BAV patients? Provided that it is a real phenotypic difference- what are the predictors of non-progressive aortopathy in BAV disease? Obviously, this issue was not the main focus of the current manuscript and no specific analysis has been performed. However, based on the presented data, risk stratification for aortic events based on BAV morphology and baseline aortic diameter would be inadequate. A higher level of complexity in determinants of BAV-associated aortopathy has been proposed by the authors. In our opinion, this question will be impossible to address without knowing the precise haemodynamic profile of transvalvular flow in these BAV patients. Moreover, the presented data underscore still significant gaps in knowledge in the development of BAV aortopathy.
1. Detaint D, Michelena HI, Nkomo VT, Vahanian A, Jondeau G, Sarano ME. Aortic dilatation patterns and rates in adults with bicuspid aortic valves: a comparative study with Marfan syndrome and degenerative aortopathy. Heart. 2014;100:126-34.
2. Mahadevia R, Barker AJ, Schnell S, Entezari P, Kansal P, Fedak PW, Malaisrie SC, McCarthy P, Collins J, Carr J, Markl M. Bicuspid Aortic Cusp Fusion Morphology Alters Aortic 3D Outflow Patterns, Wall Shear Stress and Expression of Aortopathy. Circulation. 2013 Dec 17.
3. Sievers HH, Schmidtke C. A classification system for the bicuspid aortic valve from 304 surgical specimens. J Thorac Cardiovasc Surg. 2007;133:1226-33.
4. Sabet HY, Edwards WD, Tazelaar HD, Daly RC. Congenitally bicuspid aortic valves: a surgical pathology study of 542 cases (1991 through 1996) and a literature review of 2,715 additional cases. Mayo Clin Proc. 1999;74:14-26.
5. Girdauskas E, Disha K, Secknus M, Borger M, Kuntze T. Increased risk of late aortic events after isolated aortic valve replacement in patients with bicuspid aortic valve insufficiency versus stenosis. J Cardiovasc Surg (Torino). 2013;54:653-9.
Conflict of Interest:
Don't forget radiotherapy
This is an excellent article which will help many of us who have to manage patients who are undergoing cancer treatment.
It must be remembered that many patients also undergo radiotherapy, as is acknowledged in the article. High dose radiotherapy to the thorax can cause heart failure, both systolic and restrictive, valvular dysfunction and coronary artery disease, which often presents many years later. In lymphoma survivors who have received such therapy, cardiovascular disease is the most common cause of death.
A history of thoracic radiotherapy is important to elicit when assessing patients with cardiovascular symptoms. Such patients may present with symptoms of cardiac disease at a younger age than is typical, with few traditional risk factors, and are therefore potentially at higher risk of initial misdiagnosis.
Conflict of Interest:
Cardiac Imaging Training in the United Kingdom - Rise of the Machines.
Cardiac Imaging Training in the United Kingdom - Rise of the Machines
Anna Marciniak PhD MRCP, Jessica Webb MRCP BM BCh, Ronak Rajani MD MRCP FSCCT.
Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London. SE1 7EH. United Kingdom
Address for correspondence: Dr Ronak Rajani MD MRCP FSCCT BM, Department of Cardiology, St Thomas' Hospital, Westminster Bridge Road, London, SE1 7EH. United Kingdom. Tel: +44 7866 258 572 Fax: +44 208 399 4699 Email: Ronak.Rajani@gstt.nhs.uk
There has been a steady growth in the number of cardiology trainees electing to pursue cardiac imaging as a subspecialty after achieving their core competencies. Whereas in 2004, only 12% of cardiology trainees selected cardiac imaging as a subspecialty in the United Kingdom, this has increased to 23% in less than a decade (1). This has placed cardiac imaging on par with coronary intervention as one of the premier choices of cardiology subspecialisation.
Although contemporary surveys do not explore the reasons for this increasing popularity, it is likely that this stems from the rapid evolution in computer technology and processing power over the last decade. Prior to this, cardiac imaging was often perceived to be predominantly isolated to nuclear cardiology and echocardiography. Only a handful of centres nationally had access to cardiac magnetic resonance imaging and electron beam computed tomography. In these centres, scans were largely confined to the research domain and for well-defined clinical indications. As a consequence sub-specialty cardiac imaging was a generally a less attractive option for trainees in contrast to the allure of the developments in interventional cardiology and electrophysiology.
Rise of the Machines.
By Moore's Law it is expected that the overall processing power for computers will double every two years (2). In the year 2000, a high-end computer had a processing speed of 1.3 GHz for one core, with 37.5 million transistors in a computer-processing unit. Within ten years this had increased to 2.8 GHz for a quad-core, with a staggering 904 million transistors per computer processing unit, equating to an 862% increase in power [1.3 GHz to 11.2 GHz (2.8 x 4)]. It is clear that this progress has also translated to almost simultaneous advancements in cardiac imaging.
Cardiac computed tomography.
In 2000, computed tomography scanners had a temporal resolution of 0.5 seconds with a slice count of 4 to 8. By 2005, 32/64 slice scanners began to emerge and reliable coronary imaging became a reality. Nowadays, contemporary CT scanners can achieve a temporal resolution of 75 ms with a spatial resolution of <0.6mm. The slice count has increased to 320 and other novel innovations such as dual-source and dual energy x-ray sources, high-definition detectors, iterative reconstruction techniques and advancements in the post-processing of CT datasets have also emerged. Computer power has also permitted the application of computational fluid dynamics to cardiac CT datasets to measure pressure, velocity and arterial wall stress. This development has now made it possible to evaluate lesion specific fractional flow reserve by CT and also valve haemodynamics. In the future, the prospect of being able to able non-invasively assess the coronary anatomy and its functional significance at sub 0.5 mSv doses with <20 mls of contrast is likely to become a distinct reality.
Cardiac magnetic resonance imaging.
Although magnetic resonance imaging has been available for almost twenty years, it is only up until relatively recently that it has been possible to image the beating heart. Advancements in computer processing power have had a significant impact upon this capability. Alongside high- strengths magnets and novel contrast agents, improvements in computing power have permitted extremely rapid cardiac acquisitions, advancements in respiratory compensation techniques and the assessment of tissue characteristics without the need for peripherally administered contrast (T1 mapping). We are also now witnessing advancements in coronary motion correction techniques that will enable the more widespread use of coronary magnetic resonance imaging, detailed plaque characterisation with novel contrast agents, and the development of magnetic resonance spectroscopy to assess myocardial metabolism in vivo.
Nuclear cardiology has also benefitted from computer processing power improvements over the last decade. There have been vast changes from planar to single-photon emission computed tomography, and to now ultrafast SPECT, positron emission tomography (PET), and hybrid SPECT-CT and PET-CT. Gamma camera technology has also evolved with the emergence of solid-state detectors using cadmium zinc telluride in place of conventional sodium iodide based systems. These detectors are smaller in size and offer better energy resolution and spatial resolution than conventional detectors. In addition, owing to their compact nature, new configurations with multiple detectors are now possible. These permit shorter imaging times by almost five-fold to two minutes and a substantial reduction in radiation dose owing to smaller doses of radioactive isotope being required. There has also been progress in developing newer automated quantitative methods for image processing and interpretation, molecular and hybrid imaging and perfusion tracers.
There has also been a change in the landscape of echocardiography. With technological advancements we have seen the miniaturisation of echocardiography machines to hand-held devices. This has permitted the migration of cardiac ultrasound to other specialities outside of cardiology and the emergence of "focussed", "point-of-care" or "screening" echocardiograms to facilitate early decision-making. In addition, the capability of "standard sized" echocardiography machines has also vastly increased. Cardiologists now have access to ultrasound machines that can perform 3-dimensional imaging to provide an accurate quantitative assessment of the left ventricle and heart valves. There are also novel quantitative measures of myocardial function such as myocardial strain and speckle tracking to evaluate regional and global myocardial deformation properties.
Cardiac Imaging - salvation.
For cardiology trainees these developments in cardiac imaging have had a number of effects. Firstly, we have seen rapid rise in the number of cardiology journals and international conferences dedicated solely to cardiac imaging. This reflects the substantial investment of research in these areas and the increasing profile of cardiac imaging as a sub- speciality. Secondly, there has been an increase in the number of cardiac centres within the UK providing 3 or more of these imaging modalities. In order to capitalise on this, the number of suitably trained consultants with experience in multimodality imaging experience has had to increase. Thirdly, the profile of an imaging cardiologist within a cardiology unit has evolved. They are now seen to be vitally important to clinical decision making across a wide spectrum of cardiac conditions, including patient suitability for cardiac resynchronisation therapy, electrophysiological procedures, revascularisation, structural intervention and cardiothoracic surgery. Finally, reflecting the changes to the cardiology core curriculum in 2010, there has been a propagation of cardiac imaging training opportunities within the UK. There are now dedicated training days and annual meetings hosted by the British Society of Cardiovascular Imaging, British Society of Echocardiography and the British Society of Cardiac Magnetic Resonance, and a host of training courses and regular meetings available for trainees (3). The net result is that the perception of cardiac imaging as a subspecialty has changed substantially over the years. It is a growing subspecialty with excellent career prospects, and looking at the developments on the horizon, it is likely to be so for the foreseeable future.
Acknowledgments. In 2010 Dr Rajani was the recipient of the BCS/ACC jointly funded 1-year Fellowship in Advanced Cardiac Imaging.
1.Keenan NG. 2012 BJCA trainee survey. Br J Cardiol 2013;20:8-9. 2.Moore G E. Cramming more components onto integrated circuits. Electronics Magazine. 1965. 3.Rajani R, Berman D, Underwood R. Cardiac imaging training in the United Kingdom - time for a New Dawn. Heart. 2010;96:1427.
Conflict of Interest:
Conclusions about elderly people need real elderly people
We really appreciate the clarifications offered by Alexandros Briasoulis concerning his article, but in our opinion our claim about the importance of including in the meta-analysis information only (or mostly) from elderly patients remains well founded. In this regard, the Cochrane Hypertension Group encourages to accept only studies if 70% or more of the participants meet the definition, or individual patient data are available, or data of relevant patients are provided separately allowing specific inclusion of the population as defined (1). Moreover, the inclusion of INVEST trial (2) in the ACCF/AHA 2011 (3) cannot be claimed as a relevant argument to support proceeding in the same manner in the meta-analysis, because of the inherent low level of evidence showed by consensus. On the other hand, the INVEST trial has a very high risk of bias. It is an open trial and no information on the sequence generation nor the allocation concealment is provided.
We agree with the author in the conclusion showed by the secondary analysis (4). But in fact this provides to us compelling evidence of the importance of separating the information between young and older people. Furthermore, it is not clear to us why these findings are said to be "in accordance" with the results of the sensitivity analysis performed by the author. According to the Discussion (1), the subgroup analysis of studies with patients over 70 years showed that "the beneficial effects of antihypertensive treatment remained significant in the first group of studies (treatment versus placebo group)" but the meta-analysis did not take into account blood pressure levels, thereby both papers seem to be focused on very different issues. Also, we have not been able to read in the last article cited (5) the assertion made on the J-curve association in patients above or below age of 65. In fact, this study did not compare different age subgroups any time but different blood pressure strata, and the mean age values in each 10-mm Hg blood pressure stratum were very similar (66-67 years).
In short, if elderly age begins at 65, we need to found our practices on studies including real elderly people. Evidence based on the results of studies with patients of a mean age close to 65 is not trustworthy.
(1) Gorricho J, Garjon J, Celaya MC, Muruzabal L, Montoya R, Lopez A, Malon MDM, Saiz LC. Blood pressure targets for the treatment of patients with hypertension and cardiovascular disease. Cochrane Database of Systematic Reviews 2013, Issue 1. Art. No.: CD010315. DOI: 10.1002/14651858.CD010315. (2) Pepine CJ, Handberg EM, Cooper-DeHoff RM, et al. A calcium antagonist vs a non-calcium antagonist hypertension treatment strategy for patients with coronary artery disease. The International Verapamil- Trandolapril Study (INVEST): a randomized controlled trial. JAMA. 2003;290(21):2805-16. (3) Aronow WS, Fleg JL, Pepine CJ, et al. ACCF/AHA 2011 expert consensus document on hypertension in the elderly: a report of the American College of Cardiology Foundation Task Force on Clinical Expert Consensus Documents. Circulation. 2011;123:2434-2506. (4) Denardo SJ, Gong Y, Nichols WW, et al. Blood pressure and outcomes in very old hypertensive coronary artery disease patients: an international verapamil ST-Trandolapril (INVEST) substudy. Am J Med. 18 2010;123:719-26. (5) Messerli FH, Mancia G, Conti CR, et al. Dogma disputed: can aggressively lowering blood pressure in hypertensive patients with coronary artery disease be dangerous? Ann Intern Med. 2006;144:884-93.
Luis Carlos Saiz, Pharm D Pharmacotherapy Research Coordinator Navarre Health Service, Spain
Juan Erviti, Pharm D, PhD Head of Unit, Drug Information Navarre Health Service, Spain
Conflict of Interest:
Pre-test probability in the new ESC guidelines or appropriateness criteria.
We read with great interest the recent article by Bhattacharyya et. al.1 They state that a high proportion (71/250) of stress echocardiograms (SE) were performed on low risk patients and were inappropriate, concluding that implementation of diagnostic appropriateness criteria2 would reduce this.
Appropriateness criteria2 published in 2011 reviewed clinical scenarios warranting SE and graded these on a scale of 1 to 9. Classifying patients into 3 categories, appropriate (grade 7-9), uncertain (grade 4-6) and inappropriate (grade 1-3). The 2013 ECS guidelines3 for investigation of stable coronary artery disease (CAD) recommends functional testing for patients with intermediate (15-85%) pre-test probability (PTP). However, Bhattacharyya et. al. do not elaborate on the PTP of patients in each classification. Thus, in accordance with new ESC guideline SE may have been appropriate in some of the patients classified as uncertain or inappropriate.
Furthermore, a proportion of patients classified as inappropriate included previously revascularised patients with stable symptoms. Cardiologists may feel obliged to perform investigations on symptomatic previously revascularised patients, often with invasive coronary angiography, even if they are stable with a negative SE within the previous two years. To reduce the burden on SE, cardiac CT is a viable alternative that demonstrates grafts and proximal stent patency.
Finally, NICE, ESC and ACC/AHA guidelines all differ in diagnostic guidelines, enabling cardiologists to use their experience and local expertise to select the most appropriate investigation for individual patients.
Conflict of Interest:
Re:Scaling cardiac dimensions to body size is crucial in the cardiovascular care of elite athletes
Dear Professor Pressier,
Thank you for your correspondence with respect to our study (1). We have read your paper (2) with interest and congratulate you on an important paper providing further empirical evidence to support more appropriate methods of generating body size independent cardiac indices. We are delighted your data demonstrated the importance of fat free mass something we and others have proposed empirically before and represented in previous review articles (3, 4). Your recent study is a very insightful contribution to this field and we hope others in the clinical field read this work and follow suit. We feel our additional comments in the meta- analysis support a revisionist approach to the use of cardiac indices.
We would go further though and not stop at structural data and charge all interested groups to look at how key functional data are indexed. We have some empirical data published in respect of longitudinal tissue velocities (5) and we feel this work should be extended.
References 1. Utomi V, Oxborough D, Whyte GP, Somauroo J, Sharma S, Shave R, et al. Systematic review and meta-analysis of training mode, imaging modality and body size influences on the morphology and function of the male athlete's heart. Heart 2013;99:1727-1733. 2. Pressler A, Haller B, Scherr J, Heitkamp D, Esefeld K, Boscheri A, et al. Association of body composition and left ventricular dimensions in elite athletes. European Journal of Preventive Cardiology. 2012;19(5):1194 -204. 3. Batterham A, George K, Whyte G, Sharma S, McKenna W. Scaling cardiac structural data by body dimensions: a review of theory, practice, and problems. Int J Sports Med. 1999;20(8):495-502. 4. Dewey F, Rosenthal D, Murphy DJ, Froelicher V, Ashley E. Does size matter? Clinical applications of scaling cardiac size and function for body size. Circulation. 2008;117(17):2279-87. 5. Oxborough D, Batterham AM, Shave R, Artis N, Birch KM, Whyte G, et al. Interpretation of two-dimensional and tissue Doppler-derived strain (?) and strain rate data: is there a need to normalize for individual variability in left ventricular morphology? Eur J Echocardiogr. 2009;10(5):677-82.
Conflict of Interest:
Re:Scaling cardiac dimensions to body size is crucial in the cardiovascular care of elite athletes
Dear Professor Pressier,
Many thanks for your correspondence. Your recent study is a very important contribution to this field of research.
A meta-analysis is of course dependent on the validity of the study- level metrics that are reported by authors, and this is why we inserted the very important point about allometric scaling in our discussion.
I have been confronted with this issue also when meta-analysing studies on percentage flow mediated dilation, which may not be the most precise scaling index to employ for the change in arterial diameter.
So thank you again and I personally agree with everything you say.
Conflict of Interest:
Baseline artery diameter confounds flow-mediated dilation only if a percentage change is selected as the size-scaling index
Dear Editor, Maruhashi et al. meticulously measured the flow-mediated changes in brachial artery diameter with a large sample of participants. The changes in diameter were quantified using the conventional percentage-based index (FMD%). As usual, baseline artery diameter (Dbase) was found to be substantially and negatively correlated with FMD%. So it seems that even the most robust protocols and precise measurements of arterial diameters cannot eradicate the FMD%-Dbase correlation. This is not surprising because it is the FMD% index itself that causes this Dbase-dependency .
It seems illogical to persist in quantifying endothelial "function" with FMD% when it is so erroneously dependent on the structural/morphological variable that is its denominator. The FMD% index was presumably selected to "normalise" the flow-mediated response for variability in Dbase. But the flow-mediated response itself (measured in mm) tends to be uncorrelated to Dbase, or is even inversely proportional to Dbase. The overriding problem is that FMD% "works" only if this flow -mediated response is consistently, substantially and positively proportional to Dbase. This incongruity between the nature of the physiological change and the index used to describe that change means that FMD% itself creates the substantial negative dependency of FMD% on Dbase .
Physiological explanations have been forwarded for the FMD%-Dbase correlation  but such explanations are putting the "cart before the horse". Because the output of the protocol, the FMD% index, is the source of the Dbase-dependency problem rather than the physiological changes that are occurring during the protocol, any further physiological explanations for FMD%-Dbase dependency are unsatisfactory. For example, the shear rate explanation for Dbase-dependency forwarded by Pyke et al. and repeated by Maruhashi et al. is inconsistent with the fact that FMD% depends on Dbase even when calculated from randomly-generated data with no physiological basis at all . If the flow-mediated response was scaled to Dbase properly in the first place, there would be no substantial negative correlation between these two variables, and so no need to explain and correct with other variables. Such circular logic is avoided by appropriate size scaling in the first place. Then the influence of other important variables, e.g., shear rate, on the flow-mediated response per se can be quantified more precisely.
I agree that Dbase should be taken into consideration as a confounder of FMD%. A full consideration of this problem has surfaced recently and, as in the study by Maruhashi et al., been applied to age- and sex- differences in the flow-mediated response . The FMD% index is higher in women than in men simply because FMD% does not scale properly for the lower Dbase in women. Similarly, Dbase increases with age, thus biasing age-related changes when FMD% is selected as the outcome of interest . As long as FMD% is the index used to quantify the relative flow-mediated response, such inferential errors will occur, and these errors cannot be corrected parsimoniously with any physiological mechanisms. If FMD% was replaced with a more accurate scaling index, Dbase-dependency, and the associated interpretive problems would be eradicated.
1. Maruhashi T, Soga J, Fujimura N, et al. Relationship between flow- mediated vasodilation and cardiovascular risk factors in a large community -based study. Heart 2013;991837-1842.
2. Atkinson G, Batterham AM. Allometric scaling of diameter change in the original flow-mediated dilation protocol. Atherosclerosis 2013;226:425 -427
3. Pyke KE, Dwyer EM, Tschakovsky ME. (2004) Impact of controlling shear rate on flow-mediated dilation responses in the brachial artery of humans. J Appl Physiol 97: 499-508
Conflict of Interest:
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