The heart and the waist: Relationship between abdominal fat and recurrent events after myocardial infarction

Metabolic syndrome is a disorder defined by a group of risk factors that greatly increase the risk of atherosclerotic cardiovascular disease (ASCVD). These cardiometabolic abnormalities include impaired fasting blood sugar, increased blood pressure, excess body fat around the waist and elevated cholesterol or triglyceride levels. While increased body mass index (BMI) is associated with increased all-cause mortality and ASCVD, abdominal obesity, in particular, is a better independent predictor of cardiovascular events. The negative impact of visceral fat in patients’ metabolic profile and biventricular heart function could be the basis for these findings. In this issue of the European Journal of Preventive Cardiology, Mohammadi et al. report the association between waist circumference and ASCVD in a postmyocardial infarction population. In this retrospective analysis, 22,882 patients were assessed from the SWEDEHEART registry from 2005 to 2014. Recurrent ASCVD was defined as non-fatal myocardial infarction, coronary heart disease death, non-fatal or fatal ischaemic stroke. Seven per cent of the patients had an ASCVD event during a median follow-up time of approximately four years. Waist circumference was an independent predictor of an ASCVD event even when adjusted by age, gender, smoking status, left ventricle ejection fraction, systemic arterial hypertension, systolic blood pressure, non-sinus rhythm electrocardiogram, diabetes mellitus type 2, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, BMI and medical therapy. Patients of the fourth and fifth quintile (waist circumference more than 104 cm and 110 cm for men and 97 cm and 106 cm for women, respectively) had a 21% and 23% increased relative risk of a cardiovascular event. The strengths of this paper by Mohammadi et al. include the large cohort, with over 22,000 patients, the long follow-up period and the considerable number of ASCVD events. There is comfort in numbers, and this large population provides the necessary statistical power for the necessary adjustment for a myriad of ASCVD risk factors and potential confounders. However, it is also important to acknowledge some limitations of this study. First, being retrospective in nature, a potential selection bias from missing data may be an issue. Second, residual confounding cannot be excluded, even though the list of confounding variables assessed in the multivariate regression was appropriate and extensive. Third, in subgroup analysis, it seems that waist circumference was a better predictor of cardiovascular events in men than in women. One likely reason may be the lower number of absolute events in the female population, but other factors may play a significant role. Finally, coronary artery lesion characteristics and the completeness of revascularization are important determinants of recurrence of ASCVD after a first myocardial infarction, and these were not evaluated in this study. In conclusion, Mohammadi et al. showed an independent association between increased waist circumference and cardiovascular events after myocardial infarction, adding waist circumference to the long list of prognosticators after an acute coronary syndrome. Perhaps more importantly, these findings underline the importance of this easily recognizable yet frequently overlooked risk marker.