Development and Validation of a Prognostic Index for Risk Stratification of Patients with Early Repolarization

Authors


Stavros Stavrakis, M.D., Ph.D., University of Oklahoma Health Sciences Center, Heart Rhythm Institute, 1200 Everett Dr, TCH 6E103, Oklahoma City, OK 73104. Fax: 405–271-2619; E-mail: stavros-stavrakis@ouhsc.edu

Abstract

Background: Early repolarization (ER) is associated with increased mortality in the general population. We sought to develop and validate a prognostic index (PI) of mortality in patients with ER.

Methods: We identified 852 consecutive patients (mean age 49 ± 12 years) with ER (J-point elevation ≥0.1 mV in inferior or lateral leads), from the VA electronic electrocardiogram (ECG) database. A random sample of age-matched patients with normal ECG was used as control (n = 257). The initial cohort was randomly split into a derivation and a validation cohort (2/3 and 1/3 of patients, respectively). A PI was derived from the weighed sum of the regression coefficients of each independent risk factor in the final model using Cox regression analysis.

Results: During a median follow-up of 6.4 years, 170 patients died. ER was associated with increased mortality compared to control (HR 1.49, 95% CI 1.05–2.12; P = 0.03). Older age, lower body mass index, non-African American race, current use of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers or sulfonyureas, prolonged corrected QT (QTc), and higher ER amplitude independently predicted all-cause mortality. Annualized mortality rates were 1.3%, 2.2%, and 3.7% in the low, intermediate, and high-risk groups, respectively, in the derivation cohort (log rank P < 0.0001) and 0.8%, 1.9%, and 4.1% in the low, intermediate, and high-risk groups, respectively, in the validation cohort (log rank P < 0.0001). Model discrimination was very good (c-statistic = 0.85 and 0.80 for derivation and validation cohort, respectively).

Conclusions: A PI derived from simple clinical and ECG characteristics predicts mortality in patients with ER and may be used clinically for risk stratification.

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