Hypertrophic cardiomyopathy (HCM) is a common genetic disease that may cause left ventricular outflow tract (LVOT) obstruction, heart failure, and sudden death. Recent studies have shown a high prevalence of obstructive sleep apnea among patients with HCM. Because the hemodynamics of patients with LVOT obstruction are unstable and depend on load conditions to the heart, we evaluated the acute effects of CPAP on hemodynamics and cardiac performance in patients with HCM.
We studied 26 stable patients with HCM divided into nonobstructive-HCM (n=12) and obstructive-HCM (n=14) groups (LVOT gradient pressure lower or higher than 30 mm Hg, respectively). Patients in the supine position while awake were continuously monitored by beat-to-beat blood pressure and electrocardiography. A 2-dimensional echocardiography was performed at rest (Baseline) and after 20 minutes of nasal CPAP at 1.5 cmH2O and 10 cmH2O, which was applied in a random order interposed by 10 minutes without CPAP.
Blood pressure, cardiac output, stroke volume, heart rate, left ventricular ejection fraction and LVOT gradient did not change during the study period in either group. CPAP at 10 cmH2O decreased right atrial size and right ventricular relaxation in all patients. CPAP at 10 cmH2O decreased left atrial volume significantly and decreased right ventricular outflow acceleration time, suggesting an increase in pulmonary artery pressure in obstructive patients.
The acute application of CPAP is apparently safe in patients with HCM because CPAP does not lead to hemodynamic compromise. Long-term studies in HCM patients with sleep apnea and nocturnal CPAP are warranted.