Introduction: Although it has been implicated that the association between low skeletal muscle mass and cardiovascular diseases, the prognostic value of skeletal muscle mass in patients with ST-segment elevation myocardial infarction (STEMI) is unclear.
Hypothesis: We assessed the hypothesis that low skeletal muscle mass index (SMMI) is associated with an increased risk of secondary cardiovascular events in patients with STEMI.
Methods: We enrolled 303 patients with STEMI. SMMI was evaluated with dual-energy X-ray absorptiometry scan before discharge. The patients were divided into low and high SMMI groups using the first tertile of SMMI (≤ 6.822 kg/m2 for men and ≤ 5.271 kg/m2 for women). Patients were followed for cardiovascular events, which consist of death, myocardial infarction, ischemic stroke, congestive heart failure, and revascularization.
Results: During follow-up (median 22 months [interquartile ranges 12 and 29 months]), 42 patients experienced cardiovascular events (8 death, 9 myocardial infarction, 6 ischemic stroke, 3 congestive heart failure, and 16 revascularization). The event rate at 22 months after STEMI was significantly higher in patients with low SMMI than those with high SMMI (26.1% vs 11.4%, log-rank p < 0.001) (Figure). Even after adjustment with age, gender, and estimated GFR, patients with low SMMI had 2.7-fold higher risk of cardiovascular events compared to those without (Adjusted hazard ratio 2.73, 95% confidence interval 1.38 to 5.50, p = 0.004). Low SMMI was significantly more frequent in the older group (age ≥ 65) than younger group (age <65) (45.6% vs 7.9%, p < 0.001), and the impact of low SMMI on cardiovascular outcomes were similar between these two groups (interaction p = 0.99).
Conclusion: Among patients with STEMI, low SMMI was significantly and independently associated with an increased risk of future cardiovascular events.