Impact of sleep-disordered breathing on myocardial damage and metabolism in patients with chronic heart failure

Sleep-disordered breathing (SDB) has a critical association with mortality and morbidity of patients with chronic heart failure (CHF). Troponin T is a marker of ongoing myocardial damage and predicts adverse clinical outcomes in patients with CHF. Carnitine plays an important role in the utilization of fatty acids in the myocardium. It has been reported that myocardial carnitine levels decrease in the failing heart. We hypothesized that plasma troponin T and carnitine are increased due to the leakage from damaged cardiomyocytes or the alteration of myocardial metabolism in CHF patients with SDB. We examined the relation of plasma troponin T and carnitine levels with severity of SDB in CHF. We used portable sleep monitor and measured the apnea–hypopnea index (AHI), plasma levels of high-sensitive troponin T and carnitine in 131 CHF patients. These patients were divided into three groups based on AHI: group A (None–mild SDB AHI < 15/h, n = 45), group B (Moderate SDB 15 ≤ AHI < 30/h, n = 32) and group C (Severe SDB AHI ≥ 30/h, n = 54). Levels of high-sensitive troponin T and plasm total carnitine were significantly higher in group C than in groups A and B [high-sensitive troponin T; group A 0.009 (0.005–0.016), group B 0.012 (0.006–0.021), group C 0.021 (0.011–0.039) ng/ml, total carnitine; group A 61.0 ± 15.1, group B 65.0 ± 13.5, group C 73.3 ± 17.5 μmol/l, P < 0.01 vs. group A and P < 0.05 vs. group B, respectively]. Furthermore, in the multiple regression analysis, the independent factors to determine plasma levels of log (high-sensitive troponin T) were high-sensitive C-reactive protein and AHI, and the independent factors to determine plasma levels of carnitine were glomerular filtration rate and AHI. The present study suggests that SDB is associated with latent myocardial damage and alteration of myocardial carnitine metabolism in patients with CHF, presented by higher circulating troponin T and carnitine levels.