Before Coming to the Conclusion That Inclusion Body Myositis Is a Risk Factor for a Heart Attack, All Influencing Factors Must Be Taken Into Account

Abstract

We were interested to read the article by Beecher et al. on a retrospective cohort study of 50 patients with inclusion body myositis (IBM) to determine whether cardiovascular risk, specifically myocardial infarction (MI), cardiomyopathy (CMP), heart failure (HF), ischemic stroke (IS) and peripheral arterial disease (PAD), was increased in this cohort [1]. It was found that patients with IBM had an increased risk of MI compared with reference patients and that IBM was not associated with an increased risk of IS, CMP, or HF [1]. The study is noteworthy, but several points should be discussed. The first point is that IBM can be both sporadic and hereditary. Since cardiovascular risk may be different in hereditary and sporadic IBM, it should be stated how many individuals had sporadic and how many had hereditary IBM. In rare cases, IBM can also be paraneoplastic and associated with malignancy [2]. Did any of the 50 included patients have a history of malignancy? The second point is that the number of patients with IBM included was small and the group sizes of the control group and the IBM cohort were very unequal. These methodological weaknesses make it questionable whether the conclusions drawn are really reliable. The third point is that atrial fibrillation (AF) was not included in the analysis [1]. Since the outcome parameters also included IS, HF, and PAD, it would have been imperative to include AF in the analysis. AF can even be a complication of MI, HF, or CMP. How many in the IBM group and how many in the control group had AF or were anticoagulated? The fourth point is that there is a large difference in the rate of statin use between the patients with IBM (24%) and the control subjects (41%) [1]. Since hyperlipidemia is a cardinal risk factor for cardiovascular disease, the increased risk of MI in patients with IBM may simply be due to this difference in statin use. The fifth point is that patients with IBM were significantly less mobile (74% had a gait disturbance) than control subjects (44% had a gait disturbance) [1]. Since regular physical activity can prevent MI [3], the increased rate of MI in patients with IBM may simply be due to their immobility. The sixth point is that 44% of patients with IBM received glucocorticoids. Corticosteroids are known to increase the risk of MI [4]. It is also known that corticosteroids increase the risk of thrombosis [5]. There is a discrepancy between the numbers given in the abstract and the number given in the results section. In the summary, the use of statins in patients with IBM compared with controls was reported as similar (28 vs. 38%), whereas in Table 1, this figure was (24% vs. 41%) [1]. This discrepancy should be clarified. It is also unclear what the authors mean by “cardiomyopathy” as an outcome parameter. Do they mean coronary artery disease, ischemic cardiomyopathy, or something else? To summarize, the conclusion that IBM is associated with an increased risk of MI is questionable. Josef Finsterer: conceptualization, investigation, methodology, validation, writing – review and editing. Sinda Zarrouk: writing – review and editing, validation. The authors have nothing to report. The authors have nothing to report. The authors have nothing to report. The authors declare no conflicts of interest. This is a linked article to E. Naddaf ‘Reply to: “Before Coming to the Conclusion That Inclusion Body Myositis Is a Risk Factor for a Heart Attack, All Influencing Factors Must Be Taken Into Account”.’ To view this article, visit https://doi.org/10.1111/ene.70295. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.