Ischaemic heart disease

Improving triage of chest pain: man and computer combined? ▸ In US studies, 2% of acute myocardial infarction (MI) and 2% of unstable angina patients are wrongly triaged as low risk and sent home. These patients suffer a 1.9× higher mortality than those treated appropriately. This study compared physicians to a computer model for 20 simulated scenarios. The experience level of physicians did not affect performance, and all were more cautious than the model, leading to lower sensitivity (85% v 96%, p = 0.02). However, physicians sent home 2.4% of patients when complications would have occurred versus 0.6% for the model. Physicians may be able to use the model, combined with biochemical markers, to improve their performance. Since the model requires a history to be properly taken, the physician has not (yet) become redundant.

30% of patients with ST elevation MIs miss out on treatment ▸ A multinational registry found that, of 1763 patients with ST elevation MI (STEMI) presented within 12 hours of symptom onset, 30% did not receive appropriate reperfusion treatment. Mortality was 5% with treatment and 10% without. In hospitals with catheter labs, 19% of cases had angioplasty (these centres were almost all in the USA). This registry confirms that the older patient, the diabetic, and those with previous grafts miss out on thrombolysis.

Gp IIb/IIIa blockers reduce 30 day mortality by 1% in ACS ▸ This is a meta-analysis of the use of glycoprotein (Gp) IIb/IIIa blockers in over 30 000 patients with acute coronary syndromes (ACS). Overall 30 day mortality has been reduced from 11.8% to 10.8% by treatment (relative risk reduction 0.91, p = 0.015). The same risk reduction is present in most patient groups, with those at highest risk gaining most benefit. Bleeding was increased from 1.4% to 2.4% (p < 0.0001), but there was no rise in intracranial bleeds. The benefits of Gp IIb/IIIa blockers were additional to aspirin and unfractionated heparin. This analysis of the available data suggests that we should be treating the ACS patients with aspirin, heparin, and a Gp IIb/IIIa blocker for the first few days, performing an angioplasty, and then keeping them on clopidogrel for up to nine months. It is unclear if any UK hospital is achieving this goal.

Use aspirin when CHD risk is > 1% per year ▸ Although aspirin is a relatively safe drug, the bleeding risk outweighs its cardiovascular benefits in some patients. The choice is most difficult in low coronary heart disease (CHD) risk groups. US guidelines have been published which review the evidence and suggest a 5% five year CHD risk as the cut off. The possible added benefits of clopidogrel are obviously counterbalanced by its much higher cost, making it less suitable for low risk patients.

Easier to take a pill than change the lifestyle, but not as effective as the combination ▸Dietary treatment and HMG-CoA reductase inhibitors have been shown, in secondary prevention trials, to reduce cardiovascular morbidity and mortality. The effects of diet and simvastatin are independent and additive. Simvastatin increased insulin concentrations and reduced antioxidants compared to diet alone.

Viagra safety data in CHD patients ▸ Erectile dysfunction is common in the CHD population. Sildenafil (Viagra) is increasingly seen as the solution. This study assessed exercise performance on a supine bicycle with placebo or sildenafil 50–100 mg in 100 men with CHD. There was no difference in the extent of ischaemia on ECG or echocardiography, but blood pressure was 7 mm Hg lower (p < 0.001) in the sildenafil group. None were on nitrates.

CABG in the octogenarian is as safe as at 70 ▸ Coronary artery bypass graft (CABG) surgery is not usually offered for prognostic benefit in the over 70s, but if it is needed, can it be safely done? Most units now accept patients over the age of 70. Smith and colleagues looked at 1034 patients over a three year period and demonstrated equivalent rates for early death (3.3–5.7%) and total length of stay (12 days) in those aged 70–74, 75–79, and over 80 years. Only 71 patients over 80 years old were included. Rosengart and colleagues studied 100 consecutive cases over age 80 operated on in one institution. Mortality at 30 days was 7%, with an average stay of 17 days. Major complications occurred in 14%, but overall, median survival was about two years for CABG, three years for CABG plus valve surgery, and four years for patients with valve surgery alone. In particular, quality of life was improved in the majority of patients.

Both PTCA and stenting in small diabetic vessels are bad ▸ Angioplasty in small vessels (2–2.9 mm diameter) is associated with high restenosis rates, especially after stenting. The 100 diabetic patients in a randomised trial of small vessel stenting versus coronary angioplasty (PTCA) has shown that both groups had a 44% restenosis rate at one year. Further, revascularisation was required in 20–25%. The new coated stents, which may drastically reduce in-stent restenosis rates, are eagerly awaited, particularly for this group of patients.

Brachytherapy for in-stent restenosis ▸ Stents reduce restenosis rates, but once restenosis occurs (as it does in 10–30% of cases), treatment options are limited. Any percutaneous intervention will cause re-restenosis in up to 50% of cases. β Radiation delivered at the time of such treatment has been shown to reduce this recurrence rate. In a trial of 332 patients with diffuse in-stent restenosis, 24 (15%) patients in the irradiated group suffered death, MI, or repeat target lesion revascularisation at nine months versus 15 (31%) in the placebo group (difference 16%, 95% confidence interval (CI) 7% to 25%, p = 0.0006). Angiographic restenosis rate was lower in the radiated group than the placebo group for the entire analysed segment (26% v 52%, p < 0.0001). Again the advent of coated stents may limit the use of this technology.

Heart failure

Use of ACE inhibitors in dialysis patients ▸ Angiotensin converting enzyme (ACE) inhibitors can cause renal failure and hyperkalaemia in the patient with renal function of their own. It might be thought that this would not be a problem in anuric patients on haemodialysis; however, in such patients the risk of a potassium concentration greater than 5.5 mmol/l is 2.2× (95% CI 1.4 to 3.4) higher in those on ACE inhibitors.

Moderate alcohol consumption and heart failure ▸ Data from the Framingham study suggest that moderate alcohol consumption reduces the risk of heart failure, presumably by protecting against CHD. Men taking > 15 drinks per week were still not at higher risk than non-drinkers. Once alcoholic cardiomyopathy has developed, abstinence (or < 4 drinks per day) improved cardiac function compared to continued heavy drinking.

Hypertension

White coat hypertension may need treatment ▸ Normotensive (NT) (day time blood pressure (BP)< 130/80 mm Hg, clinic BP<135/85 mm Hg), clinic only hypertensive (COHT), and always hypertensive (HT) (BP > 140/90 mm Hg always) patients were enrolled and the NT and COHT groups matched for daytime BP, while the COHT and HT groups were matched for clinic BP. COHT may not be benign as this group had significantly more left ventricular hypertrophy and more diastolic dysfunction than the NT group.

General cardiology

Internal or external cardioversion of AF? ▸ The left atrium remains stunned after cardioversion for atrial fibrillation (AF). External cardioversion uses up to 360 J, whereas internal cardioversion can be performed with as little as 3 J. Matching for aetiology and duration of AF, as well as left atrial size, 59 patients randomly assigned to either internal or external cardioversion showed no difference in the recovery of left atrial contraction. While the right atrium wakes up immediately, the left atrium only begins the recovery after one week. There is no difference in recovery rates between the two methods of cardioversion.

Chest pain, dyspnoea, and a positive troponin I ▸ Careful, it could be a pulmonary embolism (PE). In a series of 24 large PEs, 20.8% had a troponin I concentration of > 0.4 μg/l, with one having a concentration of 2.3 μg/l. The source is presumably the right ventricle, suffering under the sudden increase in workload and the reduced arterial oxygen saturation.

Hypothermia after resuscitation of VF reduces brain damage ▸ Patients at high risk of brain injury (5–15 minutes of arrest before resuscitation, with restoration of circulation within 60 minutes) were randomised to 24 hours of hypothermia (32–34°C) or standard care. Mortality at six months was 41% (57 of 137) in the hypothermia group versus 55% (76 of 136) in the normothermia group (risk ratio 0.74, 95% CI 0.58 to 0.95). The complication rate did not differ significantly between the two groups. Neurological outcomes were also better with hypothermia. The investigators estimate that if seven patients were treated this way, one life would be saved. Only 8% of cardiac arrest patients were deemed suitable for the trial, however, leaving the field open for a larger study. In a smaller study of 77 patients, Bernard showed a similar improvement in neurological outcome with hypothermia (odds ratio for discharge home/residential home of 5.25, 95% CI 1.47 to 18.76, p = 0.011), although mortality data did not reach significance.

Atrial pacing may improve sleep apnoea ▸ Patients with sleep apnoea have episodes of bradycardia associated with the hypoxic period. Increased vagal tone may have a role to play in the apnoeic episode. In 15 patients with atrial pacing (for sinus node disease or tachy–brady syndrome) and proven sleep apnoea, sleep studies were performed with pacing on demand, and then with atrial pacing set at 15 beats above the nocturnal rate. Duration of sleep was not affected, but the number of episodes of sleep apnoea were reduced by 50%. This would seem to offer a simpler solution than surgery on the pharynx or nocturnal positive pressure ventilation.

A new use for ACE inhibitors ▸ Hypoxia leads to polycythaemia. Altitudinal polycythaemia is an exaggerated response seen in some people at altitude, a condition associated with proteinuria and renal impairment. In a trial of 26 patients with this condition, those randomised to the ACE inhibitor enalapril showed a reduction in proteinuria, but also a reduction in their packed cell volume and haemoglobin.

Journals scanned

American Journal of Medicine; American Journal of Physiology: Heart and Circulatory Physiology; Annals of Emergency Medicine; Annals of Thoracic Surgery; Archives of Internal Medicine; BMJ; Chest; European Journal of Cardiothoracic Surgery; Lancet; JAMA; Journal of Clinical Investigation; Journal of Diabetes and its Complications; Journal of Immunology; Journal of Thoracic and Cardiovascular Surgery; Nature Medicine; New England Journal of Medicine; Pharmacoeconomics; Thorax

Reviewers

C Baker, E Barnes, V Bhatia, R Desilva, M Earley, K Fox, D Gorog, G Jenkins, R Kaprilian, A Kapur, M Khan, P Lambiese, V Markides, M Poullis, P Ramrakha, J Strange, B Wasan, H Walker