Usefulness of the electrocardiogram in predicting cardiovascular mortality in asymptomatic adults with aortic stenosis (from the Simvastatin and Ezetimibe in Aortic Stenosis Study)

Abstract

Hypertension and coronary heart disease are common in aortic stenosis (AS) and may impair prognosis for similar AS severity. Different changes in the electrocardiogram may be reflective of the separate impacts of AS, hypertension, and coronary heart disease, which could lead to enhanced risk stratification in AS. The aim of this study was therefore to examine if combining prognostically relevant electrocardiographic (ECG) findings improves prediction of cardiovascular mortality in asymptomatic AS. All patients with baseline electrocardiograms in the SEAS study were included. The primary end point was cardiovascular death. Backward elimination (p >0.01) identified heart rate, Q waves, and Cornell voltage-duration product as independently associated with cardiovascular death. Multivariate logistic and Cox regression models were used to evaluate if these 3 ECG variables improved prediction of cardiovascular death. In 1,473 patients followed for a mean of 4.3 years (6,362 patient-years of follow-up), 70 cardiovascular deaths (5%) occurred. In multivariate analysis, heart rate (hazard ratio [HR] 1.5 per 11.2 minute(-1) [1 SD], 95% confidence interval [CI] 1.2 to 1.8), sum of Q-wave amplitude (HR 1.3 per 2.0 mm [1 SD], 95% CI 1.1 to 1.6), and Cornell voltage-duration product (HR 1.4 per 763 mm × ms [1 SD], 95% CI 1.2 to 1.7) remained independently associated with cardiovascular death. Combining the prognostic information contained in each of the 3 ECG variables improved integrated discrimination for prediction of cardiovascular death by 2.5%, net reclassification by 14.3%, and area under the curve by 0.06 (all p ≤0.04) beyond other important risk factors. ECG findings add incremental predictive information for cardiovascular mortality in asymptomatic patients with AS.

Trial registration: ClinicalTrials.gov NCT00092677.