What is the clinical evidence from this study?

Study design: Observational. Population: Healthy Caucasian families (n=459). Intervention: Genetic factors (Heritability). Primary outcome: Heritability (h2) of left ventricular mass with full adjustment (h2 = 0.23, p=0.025).

March 11, 2011Open Access

Heritability of left ventricular structure and function in Caucasian families

Key Result

Genetic factors demonstrated moderate heritability for left ventricular mass (h2 = 0.23, P = 0.025) and tissue Doppler imaging-derived mitral annular Ea and Aa peaks (h2 = 0.36 and 0.53, respectively).

Study Design

Type

Observational (n=459)

Structured PICO

Population

459 white European subjects from 52 families, free of clinically significant heart disease and antihypertensive treatment, underwent echocardiography to assess the heritability of left ventricular traits.

Outcome

Heritability of left ventricular structural and functional traits (LV mass, mitral annular velocities Ea and Aa, mitral inflow A and E peaks)surrogate

The study demonstrates moderate heritability for LV mass and mitral annular Ea and Aa peaks, supporting further research to map genetic variants contributing to LV structural and functional phenotypes.

Main Result

Effect estimate: h2 = 0.23

p-value: p=0.025

Limitations

Moderate sample size compared with some other population studies.
Exclusion of subjects on antihypertensive drug treatment might have diminished the power to demonstrate heritability.
Left ventricular mass was calculated from echocardiography rather than cardiac MRI, which might have resulted in an underestimation of heritability due to random measurement error.
Did not investigate the heritability of left ventricular mass indexed by body weight or body surface area.

Abstract

AIMS: The aim of this study was to investigate the heritability as well as genetic and environmental correlations of left ventricular (LV) structural and functional traits in complex pedigrees of a Caucasian population. METHODS AND RESULTS: We randomly recruited 459 white European subjects from 52 families (50% women; mean age 45 years). LV structure was measured by M-mode and 2D echocardiography and LV function was measured by conventional Doppler and tissue Doppler imaging (TDI). Other measurements included blood pressure, anthropometric, and biochemical measurements. We estimated the heritability of LV traits while adjusting for covariables, including sex, age, body height and weight, systolic and diastolic blood pressures, and heart rate. With full adjustment, heritability of LV mass was 0.23 (P= 0.025). The TDI-derived mitral annular velocities Ea and Aa showed moderate heritability (h(2)= 0.36 and 0.53, respectively), whereas the mitral inflow A peak had weak heritability (h(2) = 0.25) and the E peak was not heritable (h(2) = 0.11). We partitioned the total phenotypic correlation when it reached significance, into a genetic and an environmental component. The genetic correlations were 0.61 between the E and Ea peaks and 0.90 between the A and Aa peaks. CONCLUSION: Our study demonstrated moderate heritability for LV mass as well as the mitral annular Ea and Aa peaks. We also found significant genetic correlations between the E and Ea peaks and between the A and Aa peaks. Our current findings support the ongoing research to map and detect genetic variants that contribute to the variation in LV mass and other LV structural and functional phenotypes.

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