3151The prognostic meaning of a reduced reserve of left ventricular force during exercise in hypertrophic cardiomyopathy

Abstract

Abstract Background Hypertrophic cardiomyopathy (HCM) patients with blunted force-frequency relationship assessed with pacing during cardiac catheterization are at greater risk of adverse events. Left ventricular contractile reserve (LVCR) based on force can be obtained noninvasively during exercise stress echocardiography (ESE). Purpose To evaluate the prognostic correlates of force-based LVCR during ESE in HCM. Methods We enrolled 332 HCM patients (age 51±15 years, 193 males, New York Heart Association, NYHA, Class I-III, EF 68±9%, maximal wall thickness 20±5 mm, left ventricular outflow tract gradient, LVOTG, present at rest in 34 pts, 10%) referred for ESE in 7 quality-controlled labs. SE assessment included LVOTG (mm Hg), LV Force (systolic blood pressure by cuff sphygmomanometer + LVOTG/LV end-systolic volume assessed with 2-D, mmHg/ml) and LVCR (peak/rest ratio of LV Force). LV volumes were measured from apical biplane (4- and 2-chamber) views with Simpson method when feasible (n=290) or with linear Teichholz (T) method from parasternal (long- or short-axis) view (n=42). All patients were followed-up. Results Force values were 8.5±6.7 at rest and 15.0±13.7 mmHg/mL at peak stress (P<0.001). During a median follow-up time of 58 months, 50 patients experienced at least one event: 19 deaths (10 cardiac), 9 hospitalizations for acute heart failure, 16 myotomy/myectomy and 22 atrial fibrillations. The event-free survival was lower in the 195 patients with LVCR <1.77 (identified with Receiver-Operator Characteristic analysis) compared to the 137 with LVCR ≥1.77: see figure. Multivariate analysis identified LVCR (Hazard ratio, HR, 2.032, 95% confidence intervals, CI, 1.042–3.964, P=0.037), age (HR, 1.033, 95% CI 1.009–1.058, P=0.007) and NYHA class (HR 2.204, 95% CI 1.161–4.185, P<0.016) as independent predictors of events. Figure 1. HCM-LVCR Conclusion A non-invasive evaluation of LVOTG, systolic blood pressure and LV end-systolic volume during ESE allows to assess force-based LVCR in HCM. Lower LVCR is associated with greater risk of events at follow-up.