Obese patients with elevated right ventricular systolic pressure (RVSP) by echocardiography (ECHO) are often diagnosed with pulmonary arterial hypertension (PAH) but may not actually have it. We sought to better characterize such patients.
A review of our catheterization data in obese patients presenting with suspected PAH based upon an abnormal ECHO, suggested that diastolic dysfunction and not PAH was frequently the etiology of the elevated RVSP. We further evaluated these obese patients with normal left ventricular (LV) systolic function, an elevated pulmonary capillary wedge pressure (PCWP) and normal to mildly elevated pulmonary vascular resistance (PVR) (<3 Wood units).
29 individuals had a mean pulmonary arterial pressure (mPAP) > 25 mm Hg, normal LV systolic function and PCWP > 15 mm Hg and a PVR < 3 Wood units (likely diastolic dysfunction). Thirteen of this cohort had conditions expected to contribute to PAH including congenital heart disease (3), connective tissue disease (4), high cardiac output syndromes (2). Four patients had left-sided or valvular heart disease. The remaining 16 patients as well as 7 with PVR 3 to 5 Wood units had some combination of obesity, a sleep disorder or hypertension as contributing factors. All 23 had poorly controlled hypertension and obesity with body mass index (BMI) > 30, with mean BMI of 43.9 (range 30.9 to 65). Fourteen (66.7%) had morbid obesity (BMI >40). Seventeen (74%) had known obstructive sleep apnea. Twelve had normal right ventricular (RV) size on ECHO, while nine had mildly enlarged right ventricles. Two patients had initial ECHO with moderately enlarged right ventricles but all had normal RV function.
The combination of hypertension, sleep apnea, and obesity in these patients is likely contributing to the apparent diastolic dysfunction and resulting mild PH.
It should not be assumed that patients with an elevated RVSP by ECHO have PAH. PCWP and diastolic dysfunction may be causative. Complete evaluation including cardiac catheterization prior to therapy for PH is essential. This population merits further study.
Terry Fortin, None.