Usefulness of quantitative assessment of electrocardiographic ST depression for predicting new-onset heart failure in American Indians (from the Strong Heart Study).

The qualitative electrocardiographic strain pattern of ST depression (STD) and T-wave inversion is strongly associated with coronary heart disease and left ventricular hypertrophy and is an independent predictor of new-onset heart failure in hypertensive participants. However, whether quantitative measures of STD in the lateral precordial leads predict new heart failure is unclear. Digital electrocardiograms were examined in 2,059 American-Indian participants in the second Strong Heart Study examination with no history of heart failure. The absolute magnitude of ST segment deviation was measured using computer to the nearest 5 microV in leads V(5) and V(6). During 5.7 +/-1.4 years of follow-up, heart failure developed in 77 participants (3.7%). Participants who developed heart failure had greater STD in leads V(5) or V(6) (-11 +/- 35 vs 12 +/- 27 microV; p <0.001) than those who did not. In univariate Cox analyses, STD was a significant predictor of new heart failure, with each 10-microV greater STD associated with a 31% greater risk of heart failure (hazard ratio [HR] 1.31, 95% confidence interval [CI] 1.24 to 1.39). Increasing STD grouped according to quartiles was strongly associated with the development of heart failure, with stepwise increasing risk of heart failure compared with the lowest quartile of STD for the second (HR 2.39, 95% CI 0.77 to 7.40), third (HR 3.01, 95% CI 1.00 to 9.08), and fourth quartiles of STD (HR 9.06, 95% CI 3.26 to 25.16). In Cox multivariate analyses controlling for age, gender, diabetes, coronary heart disease, albuminuria, and other baseline risk factors, STD remained a significant predictor of incident heart failure (HR 1.22, 95% CI 1.13 to 1.32 per 10-muV increment in STD; p <0.001). In conclusion, increasing STD in lateral precordial leads is strongly associated with increased risk of developing heart failure independent of other risk factors for new heart failure.