Changes in left ventricular filling and left atrial function six months after nonsurgical septal reduction therapy for hypertrophic obstructive cardiomyopathy

OBJECTIVES The purpose of this study was to evaluate changes in left ventri cular (LV) filling, left atrial (LA) volumes and function six months after nonsurgical septal reduction therapy (NSRT) for hypertrophic obstructive ca rdiomyopathy (HOCM). BACKGROUND Patients with HOCM frequently have enlarged left atria, which pr edisposes them to atrial fibrillation. Nonsurgical septal reduction therapy results in significant reduction in left ventricular outflow tract (LVOT) obstruction and symptomatic improvement. However, its effect on LV passive filling volume, LA volumes and function is not yet known. METHODS Thirty patients with HOCM underwent treadmill exercise testing as w ell as 2-dimensional and Doppler echocardiography before and six months aft er NSRT. Data included clinical status, exercise duration, LVOT gradient, m itral regurgitant (MR) volume, LV pre-A pressure and LA volumes. Left atria l ejection force and kinetic energy (KE) were computed noninvasively and we re compared with 12 age-matched, normal subjects. RESULTS New York Heart Association (NYHA) class was lower and exercise dura tion was longer (p < 0.05) six months after NSRT. The LVOT gradient, MR vol ume and LV pre-A pressure were all significantly reduced. HOCM patients had larger atria, which had a higher ejection force and KE, compared with norm al subjects (p < 0.01). After NSRT, LV passive filling volume increased (p < 0.01), whereas LA volumes, ejection force and KE decreased (p < 0.01). Re duction in LA maximal volume was positively related to changes in LV pre-A pressure (r = 0.8, p < 0.05) and MR volume (0.4, p < 0.05). Changes in LA e jection force were positively related to changes in LA pre-A volume (r = 0. 7, p < 0.01) and KE (r = 0.81, p < 0.01). The increase in exercise duration paralleled the increase in LV passive filling volume (r = 0.85, p < 0.05). CONCLUSIONS Nonsurgical septal reduction therapy results in an increase in LV passive filling volume and a reduction in LA size, ejection force and KE . (J Am Coll Cardiol 1999;34:1123-8) (C) 1999 by the American College of Ca rdiology.