Prognostic value and temporal behavior of the planar QRS-T angle in patients with nonischemic cardiomyopathy.

BACKGROUND

The planar QRS-T angle can be easily obtained from standard 12-lead ECGs, but its predictive ability is not established. We sought to determine the predictive ability of the planar QRS-T angle in patients with nonischemic cardiomyopathy and to assess QRS-T angle behavior over time.

METHODS AND RESULTS

Baseline QRS-T angles from 455 patients in the Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation (DEFINITE) trial were measured. All patients had nonischemic cardiomyopathy, New York Heart Association class I to III heart failure, and nonsustained ventricular tachycardia or frequent ventricular ectopy. The primary end point (a composite of total mortality, appropriate implantable cardioverter-defibrillator shock, or resuscitated cardiac arrest) occurred in 25 of 172 patients (14.5%) with a QRS-T angle < or =90 degrees and in 72 of 283 patients (25.4%) with a QRS-T angle >90 degrees (hazard ratio, 1.93; 95% confidence interval, 1.23 to 3.05; P=0.002). A QRS-T angle >90 degrees remained a significant predictor of the primary end point (P=0.039) after adjustment for treatment group, age, gender, QRS duration, left bundle-branch block, left ventricular ejection fraction, New York Heart Association class III, atrial fibrillation, and diabetes mellitus. The secondary end point (total mortality) occurred in 17 of the 172 patients (9.9%) with a QRS-T angle < or =90 degrees and in 49 of the 283 patients (17.3%) with a QRS-T angle >90 degrees (hazard ratio, 1.79; 95% confidence interval, 1.03 to 3.10; P=0.016). A sample of 152 patients with multiple follow-up ECGs was analyzed to assess temporal QRS-T angle behavior. Changes in the QRS-T angle correlated with changes in left ventricular ejection fraction and QRS duration over time (P<0.001).

CONCLUSIONS

A planar QRS-T angle >90 degrees is a significant predictor of a composite end point of death, appropriate implantable cardioverter-defibrillator shock, or resuscitated cardiac arrest in nonpaced, mild to moderately symptomatic patients with nonischemic cardiomyopathy with frequent or complex ventricular ectopy. QRS-T angles changed predictably with left ventricular ejection fraction and QRS duration.