INCREASED LEFT ATRIAL SIZE WITH OBSTRUCTIVE SLEEP APNEA AFTER MYOCARDIAL INFARCTION

Background: Left atrial enlargement predict mortality after myocardial infarction (MI). In healthy subjects a simulated obstructive sleep apnea episode acutely changes the left atrial volume index (LAVi). Therefore, we hypothesized that the presence and severity of OSA, which is highly prevalent in patients with coronary artery disease, may impact LAVi in patients who sustained an acute MI. Methods: Patients with recent MI treated with percutaneous revascularization were recruited to undergo attended overnight polysomnography. Apnea hypopnea index (AHI) was determined using standard criteria. An echocardiographic study was performed during the MI hospitalization and again after at least 3 months. Left atrial volume was calculated using the biplane area-length method, and indexed to body surface area. OSA was defined as AHI ≥ 5. Patients with recurrent infarction were excluded.

Results: A total of 57 patients (age 62 ± 12 years; 21% female) were studied, of whom 40 (70%) had OSA (AHI = 15.5 ± 15.9). The initial echocardiographic study (left ventricular ejection fraction = 54 ± 13 %, LAVi = 30 ± 9) showed a positive correlation between AHI and LAVi (r = 0.32; p = 0.015). Subsequent echocardiographic study (follow up time = 25 ± 15 months, EF 57 ± 11% , LAVi = 33 ± 10) was obtained in 40 (70%) patients. At follow up, there remained a positive correlation between AHI and LAVi (r = 0.35 and p = 0.025). The LAVi of OSA patients increased (+4 ± 1.7) during the follow up period while LAVi of patients without OSA slightly decreased (–0.7 ± 2.6).

Conclusions: This study shows a relationship between the severity of OSA and increased left atrial size in patients after STEMI. These findings may have important implications since left atrial enlargement may predict increased mortality after myocardial infarction.