Diastolic Stress Echocardiography in Patients with Hypertrophy Cardiomyopathy: Association with Exercise Capacity.

Diastolic dysfunction plays a major role in precipitating congestive heart failure (CHF) in hypertrophic cardiomyopathy (HCM) patients. In many such patients, symptoms are unmasked only during exercise, as left ventricular (LV) filling pressure is normal at rest but increase with exercise. We sought to establish if abnormal post-exercise diastolic parameters are associated with reduced exercise capacity in patients with HCM. We examined 590 asymptomatic/minimally symptomatic HCM patients (54±14 years, 57% men, body mass index 30±6 kg/m2, 84% on betablockers) with HCM by two-dimensional and Doppler echocardiography at rest and following maximal treadmill exercise echocardiography (TSE). A complete echocardiogram (including LV ejection fraction, LV thickness, LV outflow tract [LVOT] gradient, degree of mitral regurgitation [MR]) was recorded. Diastolic parameters (septal and lateral [e'] velocities of the mitral annulus, peak early [E] and late [A] mitral inflow velocity, E/A ratio, E/e', right ventricular systolic pressure [RVSP] and left atrial volume index [LAVI]) were recorded at rest and post-TSE. Exercise functional capacity was recorded and divided into <85% or >85% of age-gender predicted metabolic equivalents (AGP-METs). Following maximal exercise, 32% patients had at least moderate MR, mean LVOT gradient was 61±59 mmHg, E/A ratio was 1.2± 1.0, average E/e' ratio 12.9±1.0 and peak RVSP was 36±15 mm Hg. Only 42% patients achieved >85% of AGP-METs; mean Mets were 7±3. On multivariable logistic regression analysis, higher body mass index (odds ratio [OR] 1.05), betablocker use (OR 2.58), higher LAVI (OR 1.02), higher peak-stress LVOTG (OR 1.06), peak-stress E/e' (OR 1.04) and higher RVSP (OR 1.03) were independently associated with <85% AGP-METs achieved (all p<0.05). In conclusion, in asymptomatic/minimally symptomatic patients with HCM undergoing TSE, there is a significant and independent association between abnormal diastolic response to exercise and reduced exercise capacity in HCM. Incorporating diastolic parameters during stress echocardiography could provide incremental diagnostic utility in deciphering the exact etiology of dyspnea in such patients.