Comparison of Resting and Exercise Echocardiographic Parameters as Indicators of Outcomes in Hypertrophic Cardiomyopathy

Abstract

Both resting echocardiography and exercise echocardiography produce variables predictive of outcomes in patients with hypertrophic cardiomyopathy (HCM). The aim of the present study was to compare the respective value of resting and exercise echocardiographic parameters as indicators of clinical outcomes in patients with HCM. Resting and exercise echocardiography was performed prospectively in patients with HCM evaluated at the HCM Competence Center of Bordeaux and followed up every 6 months. A composite cardiac event was defined. One hundred fifteen patients (mean age, 51.9 ± 15.2 years; 66% men) were evaluated by echocardiography and followed for a mean period of 19 ± 11 months. Eighteen patients (16%) reached the composite end point, including 10 progressions to New York Heart Association functional class III or IV. On rest echocardiography, in patients with cardiac events during follow-up, left atrial volume index was significantly more increased, as were lateral E/E' ratio and left ventricular outflow tract (LVOT) gradient, whereas mean global longitudinal strain (GLS) expressed in magnitude (14.0 ± 2.6% vs 17.0 ± 3.6%, P < .001) and peak velocities at the lateral annulus by Doppler tissue imaging were significantly reduced compared with patients without events. At peak exercise, patients who developed cardiac events were characterized by lower ejection fractions and greater LVOT gradients (76 ± 55 mm Hg vs 40 ± 40 mm Hg, P < .002). A Cox backward-entry selection model revealed that GLS ≤ 15% at rest and LVOT gradient ≥ 50 mm Hg at peak exercise were independently associated with an increased risk for poor outcomes in patients with HCM (hazard ratios, 3.8 [P = .017] and 3.3 [P = .028], respectively). On Kaplan-Meier survival analyses, peak exercise LVOT gradient evaluation showed additive value to predict outcomes, particularly in patients with rest GLS > 15% (log-rank P = .001) and despite a resting LVOT gradient ≥ 30 mm Hg (log-rank P = .001). This study supports the value of resting GLS and of peak LVOT gradient, measured during exercise echocardiography, in identifying patients with HCM at increased risk for adverse events during follow-up.