False-negative electrocardiographic left ventricular hypertrophy in patients with obstructive sleep apnea: Significances of echocardiography and 24-hour blood pressure

Abstract

Early recognition of left ventricular hypertrophy (LVH) in patients with obstructive sleep apnea (OSA) is an important clinical issue in sleep and cardiovascular medicine. Obesity may influence discrepancies in electrocardiographic and echocardiographic LVH detection in patients with OSA. Electrocardiography (ECG), echocardiography (Echo), and 24-hour ambulatory blood pressure monitoring were performed in 80 consecutive patients with OSA and 32 age-matched controls. Patients with OSA were classified into the following groups: group 1: ECG-LVH(+) and Echo-LVH(+); group 2 (false-negative ECG-LVH): ECG-LVH(-) and Echo-LVH(+); group 3(false-positive ECG-LVH): ECG-LVH(+) and Echo-LVH(-); and group 4: ECG-LVH(-) and Echo-LVH(-).The prevalence of ECG-LVH and Echo-LVH was 27.5% (22/80) and 37.5% (30/80), respectively. False-negative ECG-LVH results (group 2) were obtained in 50.0% (15/30) of patients. Overall, there was no correlation between QRS voltage and LV mass/body surface area. The ECG axis was significantly deviated to the left in groups 1, 2 and 4 compared to the controls. RaVL and SV3+RaVL were higher in group 2 than the controls. Although the ECG axis and body mass index were similar in groups 1 and 2, LV mass/body surface area was significantly greater in group 1 than group 2. Mean 24-hour systolic and diastolic blood pressures were significantly elevated in groups 1 and 2 than groups 3 and 4. Obesity in patients with OSA may play an important role regarding differences in ECG amplitudes. Considering the high prevalence of false-negative ECG-LVH, evaluation of LVH using Echo is necessary to screen the risk of cardiovascular events in obese and hypertensive patients with OSA