Silent Heart Disease in Patients With Sleep Apnea-Hypopnea Syndrome: Usefulness of the Myocardial Performance Index

Abstract

Sleep apnea-hypopnea syndrome (SAHS) is an emerging disease with considerable cardiovascular impact. The myocardial performance index (MPI) is an echocardiographic parameter that is useful in the assessment of global myocardial function. The purpose of this study was to identify any differences in the MPI between patients with and without SAHS. We studied 120 consecutive patients referred to our department for suspected SAHS. Following the overnight sleep study and after excluding all patients with hypertension, heart disease, or invalid recordings, 54 patients with SAHS and 13 patients without the disease matched for age and body mass were analyzed. A blinded cardiologist performed Doppler echocardiography, measuring parameters related to ventricular hypertrophy, systolic function, diastolic function, and the MPI. The data were compared by chi(2) and analysis of variance. Mean (SD) ventricular mass was greater in patients with SAHS (183.17 [40.5] g) than in those without that diagnosis (149 [26] g) (P=.005). No differences were observed in systolic function (78.5% [8.95%] vs 81.6% [7%]) (P=.2), although a higher percentage of patients with SAHS had abnormal diastolic function (71.2% vs 38.5%) (P=.049). The MPI was significantly higher in SAHS patients (0.54 [0.12] vs 0.46 [0.07]) (P=.028). On its own, SAHS leads to left ventricular hypertrophy. Diastolic involvement is common in these patients, although a large number of healthy individuals who are obese also present it. The MPI is higher in SAHS and could be a useful parameter to identify patients with silent heart disease before it progresses.