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Planar QRS-T angle >90° predicts outcome in cardiomyopathy
27 June 2008
MedWire News: A planar QRS-T angle greater than 90° significantly predicts death, appropriate implantable cardioverter-defibrillator (ICD) shock, and resuscitated cardiac arrest in patients with nonischemic cardiomyopathy, researchers report.
"Many patients with ICDs do not receive appropriate shocks, and the majority of patients who experience sudden death do not meet current criteria for ICD implantation," the authors comment in the journal Circulation.
They add: "Additional criteria that improve sensitivity and specificity would be beneficial, especially if they were widely available at low cost."
The planar QRS-T angle can be easily obtained from standard 12-lead electrocardiogram (ECG), but its predictive ability is not established, they explain.
Behzad Pavri (Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, USA) and colleagues examined the predictive ability of the planar QRS-T angle in 455 patients with nonischemic cardiomyopathy taking part in the Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation (DEFINITE) trial.
All patients had New York Heart Association class I to III heart failure, and nonsustained ventricular tachycardia or frequent ventricular ectopy.
The primary end point of a composite of total mortality, appropriate ICD shock, or resuscitated cardiac arrest occurred in 14.5% of patients with a QRS-T angle ≤90°, and in 25.4% of patients with a QRS-T angle >90° (hazard ratio [HR]=1.93, p=0.002).
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, a QRS-T angle >90° remained a significant predictor of the primary end point (P=0.039).
The secondary end point of total mortality occurred in 9.9% of patients with a QRS-T angle ≤90° and in 17.3% of patients with a QRS-T angle >90° (HR=1.79, p=0.016).
Pavri and co-workers conclude: "A planar QRS-T angle >90° is a significant predictor of a composite end point of death, appropriate ICD shock, or resuscitated cardiac arrest in nonpaced, mild to moderately symptomatic patients with nonischemic cardiomyopathy with frequent or complex ventricular ectopy.
They add: "Prospective studies of the utility of the planar QRS-T angle for the prediction of sudden cardiac death and need for prophylactic defibrillator implantation in this and other patient populations are warranted."
