Left ventricular strain and myocardial work in apical hypertrophic cardiomyopathy.

Abstract

Apical hypertrophic cardiomyopathy (ApHCM) is recognized for its associated cardiovascular morbidity. Herein we describe left ventricular (LV) function and mechanics over long-term follow-up in ApHCM. A retrospective study of 98 consecutive ApHCM patients was performed (mean age: 64±15 years, 46% female) using 2D and speckle-tracking echocardiography. LV function and mechanics were characterized by global longitudinal strain (GLS), segmental strain, and myocardial work indices. Myocardial work was calculated by integrating longitudinal strain and blood pressure as estimated by the brachial artery cuff pressure, to generate an LV pressure-strain loop with adjusted ejection and isovolumetric periods. Composite complications were defined as all-cause mortality, sudden death, myocardial infarction, and/or stroke. Mean LV ejection fraction measured 67%±11% and GLS was -11.7%±3.9%. Global work index (GWI) was 1,073±349 mmHg%, constructive work was 1,379±449 mmHg%, wasted work was 233±164 mmHg%, and work efficiency was 82%±8%. In 72 patients with follow-up echocardiography, at a median of 3.9 years there was progressive impairment in GLS (-11.9% vs. -10.7%; P=0.006), GWI (1,105 vs. 989 mmHg%; P=0.02), and global constructive work (1,432 vs. 1,312 mmHg%; P=0.03), without change in wasted work or work efficiency. Atrial fibrillation (β=0.37; P<0.001), mitral annular e' velocity (β=-0.32; P=0.001), and glomerular filtration rate (β=-0.2; P=0.03) were independently associated with follow-up GLS; atrial fibrillation (β=-0.27; P=0.01) and glomerular filtration rate (β=0.23; P=0.04) were also associated with follow-up GWI. Global wasted work >186 mmHg% was predictive of composite complications (AUC =0.7, 95% CI: 0.53-0.82, sensitivity 93%, specificity 41%). ApHCM is associated with preserved LV ejection fraction but abnormal LV GLS and work indices, with progressive impairment. Important clinical and echocardiographic measures are independently predictive of long-term follow-up LV GLS, GWI and adverse events.