Predictive value of early diastolic mitral annular velocity and body mass index as markers of left ventricular relaxation: validation against invasive time constant of relaxation

AIMS: Impaired left ventricular (LV) relaxation, often assessed noninvasively by reduced early diastolic mitral annular velocity (e'); however, it is age dependent. We re-investigated the relationship between e' and the invasively measured LV relaxation time constant (τ), while accounting for LV geometry, body mass index (BMI), blood pressure, heart rate, and age, and established HF risk markers. METHODS AND RESULTS: We analysed 419 patients with suspected coronary artery disease undergoing left heart catheterisation. The τ was measured using micromanometer recordings, LV volumes by ventriculography, and mean e' (average of septal and lateral e') by echocardiography. Linear and multivariable regression analyses were used to examine relationships between e' and τ and to determine the influence of BMI, blood pressure, age, and LV geometry. Mean e' correlated weakly but significantly with τ (r = -0.27, P < 0.001). In multivariable analysis, LV end-systolic volume index (LVESVI) (β=0.520, P < 0.001), heart rate (β=-0.426, P < 0.001), BMI (β=0.110, P = 0.002), and mean e' (β=-0.088, P = 0.019) were independent determinants of τ (R2 = 0.490), whereas age was not. Predictors of e' included age (β=-0.467, P < 0.001), LVESVI (β=-0.368, P < 0.001), and BMI (β=-0.101, P = 0.015) (R2 = 0.348). τ did not independently predict e'. CONCLUSION: In this cohort, e' and τ showed only a modest association. LV geometry and BMI were independent contributors to both τ and e', while age did not significantly affect τ. The determinants of τ and the mean e' partially overlap and have distinct physiological bases. An increased BMI is associated with impaired LV relaxation.