Natural course of sleep-disordered breathing after acute myocardial infarction

The aim of this study was to test whether an improvement of left ventricular ejection fraction (EF) in the early phase after acute myocardial infarction is associated with a reduction of the severity of central and obstructive sleep apnoea. 40 consecutive patients with acute myocardial infarction underwent polysomnography and cardiovascular magnetic resonance imaging within 5 days and 12 weeks after the event to assess sleep apnoea and cardiac function. We stratified the sample in patients who improved their left ventricular EF within 12 weeks by ≥ 5% (improved EF group, ΔEF 9 ± 1%, n=16) and in those who did not (unchanged EF group, ΔEF -1 ± 1%, n=24). Prevalence of sleep apnoea (≥ 15 apnoea and hypopnoea events·h(-1)) within ≤ 5 days after myocardial infarction was 55%. Apnoea and hypopnoea events·h(-1) were significantly more reduced in the improved EF group compared with the unchanged EF group (-10 ± 3 versus 1 ± 3 events·h(-1); p=0.036). This reduction was based on a significant alleviation of obstructive events (-7 ± 2 versus 4 ± 3 events·h(-1); p=0.009), while the reduction of central events was similar between groups (p=0.906). An improvement of cardiac function early after myocardial infarction is associated with an alleviation of sleep apnoea. This finding suggests that re-evaluation of treatment indication for sleep apnoea is needed when a change in cardiac function occurs.