Prevalence of subclinical right ventricular dysfunction using tissue doppler imaging among newly diagnosed Obstructive Sleep Apnea (OSA) patients in St. Luke's Medical Center (SLMC).

BACKGROUND: Obstructive sleep apnea (OSA) is a syndrome characterized by repetitive obstruction of the upper airway during sleep, and is associated with frequent episodes of transient nocturnal pulmonary hypertension and consequently, possible right heart dysfunction. The aim of this study is to determine the prevalence of subclinical right ventricular (RV) dysfunction in newly diagnosed OSA patients.

METHODS: This is a retrospective analytical study from March 2012 to February 2013. We reviewed the recent transthoracic echocardiography results of 37 patients diagnosed with OSA determined by the apnea-hypopnea index (AHI) after an overnight polysomnography. Of these, 27 patients had complete echocardiographic data. We evaluated the RV systolic function and pulmonary artery (PA) pressure by standard echocardiography, specifically RV and right atrium (RA) diameters, tricuspid annular systolic excursion (TAPSE), pulmonary artery acceleration time (AT), systolic PA pressure; and tissue Doppler imaging for RV systolic and diastolic velocities.

RESULTS: Patients with OSA were predominantly male, obese with a body mass index of more than 30 kg/m². Seventy percent were hypertensive and 30% were diabetic. Patients with OSA had normal TAPSE and RV systolic velocity. Although no significant difference in RV systolic parameters were noted between groups, OSA patients generally had lower early diastolic and a higher late (A') annular velocities suggesting impaired relaxation. AHI and men PA dimension were correlated (p<0.0001), and PA diameter was significantly increased among OSA patients, which may signify early structural cardiac changes related to chronic transient nocturnal pulmonary hypertension.

CONCLUSION: Subclinical RV diastolic dysfunction may be prevalent among OSA patients despite having normal left ventricular function and PA pressures.