Abstract 4358: Prognostic Value of Preoperative QT Interval for Prediction of Long Term Mortality After Isolated Coronary Artery Bypass Grafting
OBJECTIVE The purpose of this study was to examine the value of computerized QT interval for prediction of long-term all cause and cardiovascular mortality in patients undergoing isolated off pump coronary artery bypass grafting (CABG).
METHODS We studied 656 consecutive patients undergoing isolated CABG between 2002 and 2008. QT intervals were preoperatively measured by computer in all 12 leads and corrected for heart rate (QTc) by use of Buzett’s formula.
RESULTS After mean follow-up of 3.1 years, there were 71 deaths from all causes, including 21 cardiovascular deaths. When patients were divided into groups by use of threshold of 460 ms, the 111 (17%) patients with QTc >=460 ms had a significantly greater all cause and cardiovascular mortality by Kaplan-Meier analyses. The actuarial 5-year all cause mortality was 54% among patients with QT >=460 ms and 12% among those with QT <460 ms (p<0.0001). The actuarial 5-year cardiovascular mortality was 32% among patients with QT >=460 ms and only 3% among those with QT <460 ms (p<0.0001). After multivariate Cox regression analyses including all potential univariate predictors, QTc remained a strong predictor of all cause mortality (hazard ratio [HR], 1.11 per 10 ms; 95% CI, 1.03 to 1.19; p=0.0048) and cardiovascular mortality (HR, 1.23 per 10 ms; 95% CI, 1.10 to 1.38; p=0.0002). Similarly, QTc >=460 ms was an independent predictor of all cause mortality (HR, 2.34; 95% CI, 1.16 to 4.69, p=0.017) and cardiovascular mortality (HR, 3.49; 95% CI, 1.03 to 11.85, p=0.045) in multivariate Cox models with other univariate predictors.
CONCLUSIONS Rate corrected QT interval is a powerful and independent predictor of long term mortality after CABG.