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Heartbeat: calcium belongs in bones not hearts
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  1. Catherine M Otto
  1. Division of Cardiology, University of Washington, Seattle, Washington, USA
  1. Correspondence to Professor Catherine M Otto, Division of Cardiology, University of Washington, Seattle, WA 98195, USA; cmotto{at}uw.edu

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Calcific aortic stenosis (AS) is characterised at the tissue level by inflammation, lipid deposition and calcification of the valve leaflets. Yet, the potential role of dietary calcium supplements in the development or progression of AS is not clear. In this issue of Heart, Kassis and colleagues1 report the association between dietary calcium supplementation and cardiovascular (CV) outcomes in a retrospective longitudinal study of 2657 patients age 60 years or older with mild-to-moderate AS. In the 39% of patients taking calcium supplements, with or without vitamin D supplementation, there was a higher risk of all-cause mortality (absolute rate (AR)=43.0/1000 person-years; HR=1.31, 95% CI (1.07 to 1.62); p=0.009), CV mortality (AR=13.7/1000 person-years; HR=2.0, 95% CI (1.31 to 3.07); p=0.001) and aortic valve replacement (AVR) (AR=88.2/1000 person-years; HR=1.48, 95% CI (1.24 to 1.78); p<0.001), compared with those not on calcium supplementation (figure 1). However, there was no association between calcium supplementation and echocardiographic changes in transaortic pressure gradient or valve area.

Figure 1

Impact of calcium and vitamin D supplementation on all-cause mortality, aortic valve replacement (AVR), and the composite outcome of death or AVR. Survival analyses were performed using the Kaplan-Meier non-parametric method. Relative to those who did not supplement (n=1292), patients who supplemented with calcium±vitamin D (n=1033), but not vitamin D alone (n=332), were at higher risk of death (adjusted HR=1.31, p=0.009) and AVR (adjusted HR=1.48, p<0.001). Patients supplementing with calcium were at higher risk of the composite outcome relative to those supplementing with vitamin D alone or who did not supplement (p<0.001 for both comparisons). The median time to AVR was 65 (43–90) months vs 70 (49–102) months vs 70 (51–103) months for calcium supplementation vs vitamin D alone vs no supplementation, respectively (p<0.001).

In the accompanying editorial Bergler-Klein2 points out that, compared with calcium supplements, dietary calcium has little influence on serum calcium availability. Importantly, ‘vitamin D supplementation alone remained neutral with respect to AVR and was not linked to any mortality increase in multivariable analyses, so that the assumed beneficial effects concerning osteoporosis and bone metabolism are maintained in patients with AS.’ Hopefully, future osteoporosis studies will focus both on benefits due to improved bone strength and risks related to adverse cardiovascular outcomes (figure 2). For now, ‘In patients with calcific AS and high-risk CV, the present study strongly adds to the evidence that long-term continuous calcium supplementation should be avoided if not mandatory.’

Figure 2

Artificial calcium supplementation and bone demineralisation in osteoporosis may activate osteoblastic transformation of the aortic valve interstitial cells. Excessive calcium may lead to higher incidence of AVR and higher CV mortality in patients with aortic stenosis. AVR, aortic valve replacement; CV, cardiovascular.

Another important study in this issue of Heart evaluated whether outcomes with COVID-19 infection were affected by pre-existing use antithrombotic (AT) therapy in patients with atrial fibrillation (AF).3 In 972 971 patients with AF and a CHA2DS2-VASc score ≥2, those on AT therapy had a lower risk of death (OR=0.92, 95% CI 0.87 to 0.96), but higher risk of hospitalisation (OR=1.20, 95% CI 1.15 to 1.26) compared with those not on AT therapy. In the 12% of patients not on AT therapy, reasons for lack of AT use included demographic factors and comorbidities. Anticoagulation compared with AT therapy was associated with lower risk of death but not hospitalisation. In contrast, non-vitamin K antagonist anticoagulation compared with warfarin was associated with a lower risk of hospitalisation but not death (figure 3).

Figure 3

Visual overview of key study findings. AC, anticoagulants; AF, atrial fibrillation; AP, antiplatelets; AT, antithrombotics; DOACs, direct oral anticoagulants; IMD, Index of Multiple Deprivation; NSAIDs, non-steroidal anti-inflammatory drugs.

Raatikainen and Lassila4 put this data in context, reminding us that AF is prone to thromboembolic complications so it is not surprising that benefit for AT therapy is seen in AF patients who are suffering from a COVID-19 infection. However, the differences between anticoagulant and antiplatelet therapy are noteworthy and it is concerning that a significant number of AF patient with a CHA2DS2-VASc score ≥2 were not on any AT therapy. Their take home message is ‘COVID-19 is a dangerous disease in patients with AF and vice versa. While not evidence of causality, the data by Hardy et al 1 imply that anticoagulation may play an important prognostic role in patients with AF with COVID-19.’

The Joint British Societies’ guidelines on management of cardiac arrest in the cardiac catheterisation laboratory5 are published in this issue of Heart with the full document online (figure 4). Kudenchuk6 provides a perspective relative to the ILCOR (International Liaison Committee on Resuscitation) recommendations and points out that these new ‘guidelines are applied to a specific place for such events—the cardiac catheterisation laboratory, and are tailored to a specific occasion—a witnessed cardiac arrest in a closely monitored patient’. He comments that ‘adapting resuscitation to this environment is sensible and the participating British Societies, which spanned a wide spectrum of specialties, are to be commended for this endeavour’. We hope these guidelines will provide a practical resource and set the standard for resuscitation in the cardiac catheterisation laboratory in the UK.

Figure 4

Protocol for resuscitation of patients who suffer a cardiac arrest in the catheter laboratory. BCIS, British Cardiovascular Intervention Society; BHRS, British Heart Rhythm Society; CPR, cardiopulmonary resuscitation; PCI, percutaneous coronary intervention; PE, pulmonary embolus; PEA, pulseless electrical activity; ROSC, restoration of spontaneous circulation; TAVI, transcatheter aortic valve implantation; VF, ventricular fibrillation; VT, ventricular tachycardia.

The Education in Heart article7 in this issue explains the paradigm of machine learning and provides a summary of the design principles involved in convolutional neural networks. The utility of this approach, particularly for medical imaging, with examples from echocardiography and computer tomographic imaging, is illustrated for the tasks of classification, regression and segmentation.

The Cardiology in Focus article8 in this issue looks at the involvement of women in the European Society of Cardiology Congress from before to during the COVID-19 pandemic. The authors conclude that ‘Despite substantial progress over the past 4 years, women remain under-represented at the ESC congress, particularly among faculty, who are likely to be more senior than abstract presenters. Although this reflects the overall under-representation of women within the ESC and in academic and clinical cardiovascular medicine, it emphasises the need to ensure international conferences adopt women-friendly policies and practices to address longstanding and avoidable gender inequalities.’

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Footnotes

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Commissioned; internally peer reviewed.