Diastolic Dysfunction Predicts Cardiorespiratory Fitness and Clinical Outcomes in Hypertrophic Cardiomyopathy
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Background
Echocardiographic indices of diastolic dysfunction are routinely obtained in hypertrophic cardiomyopathy (HCM), but their relationships with cardiorespiratory fitness and long-term clinical outcomes remain poorly defined.
Objectives
This study therefore sought to determine the extent to which E/e’, left atrial volume index (LAVi), and peak tricuspid regurgitation velocity (TRV max ) relate to peak oxygen uptake, ventilatory efficiency, their longitudinal trajectories, and clinical outcomes in HCM.
Methods
We retrospectively studied patients with HCM who completed cardiopulmonary exercise testing within 7 days of resting echocardiography. Each diastolic index was related to percent-predicted peak oxygen uptake (V̇O 2 ), ventilatory efficiency (V̇E/V̇CO 2 slope), their serial trajectories, and a composite of heart failure hospitalization, transplantation, or death.
Results
Among 441 patients with HCM (mean age 49 ± 16 years; 66% men), each SD higher E/e’, LAVi, and TRV max was independently associated with lower peak V̇O 2 (−6.0, −3.6, and −6.3 percentage points of predicted) and higher V̇E/V̇CO 2 slope (+0.9, +1.0, and +2.5; all P ≤ 0.045), nonlinearly for E/e’ with peak V̇O 2 and LAVi with V̇E/V̇CO 2 slope. On serial testing, only LAVi predicted progressively worsening V̇E/V̇CO 2 slope (+0.4/yr/SD; 95% CI: 0.13-0.68; P = 0.005). Over a median of 4.8 years, 118 of 436 patients (27.1%) reached the composite endpoint, for which LAVi was the strongest echocardiographic predictor (adjusted HR: 1.68/SD; 95% CI: 1.40-2.03).
Conclusions
In HCM, resting diastolic indices were associated with cardiorespiratory fitness, and higher LAVi was independently associated with a steeper rise in V̇E/V̇CO 2 slope and heart failure events. Resting diastolic phenotyping may complement exercise testing.
