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Influence of QRS Duration on the Prognostic Value of T Wave Alternans
Author(s) -
RASHBA ERIC J.,
OSMAN AHMED F.,
MACMURDY KAREN,
KIRK MALCOLM M.,
SARANG SAMANTHA,
PETERS ROBERT W.,
SHOROFSKY STEPHEN R.,
GOLD MICHAEL R.
Publication year - 2002
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1046/j.1540-8167.2002.00770.x
Subject(s) - medicine , qrs complex , cardiology , hazard ratio , t wave alternans , repolarization , qt interval , myocardial infarction , electrocardiography , sudden cardiac death , confidence interval , electrophysiology
T Wave Alternans and QRS Duration.Introduction: T wave alternans (TWA) is a promising new noninvasive marker of arrhythmia vulnerability that quantifies beat‐to‐beat changes in ventricular repolarization. Secondary repolarization abnormalities are common in subjects with wide QRS complexes. However, the relationship between TWA and QRS prolongation has not been evaluated. The goal of this study was to determine if QRS prolongation influences the prevalence or prognostic value of TWA. Methods and Results: The study consisted of 108 consecutive patients with coronary artery disease and left ventricular ejection fraction ≤40% who were referred for electrophysiologic studies. Patients underwent TWA testing using bicycle ergometry in the absence of beta‐blockers or antiarrhythmic drugs. The primary endpoint was the combined incidence of death, sustained ventricular arrhythmias, and appropriate implantable cardioverter defibrillator therapy. The prognostic value of TWA was assessed in the entire cohort and in two subgroups: QRS < 120 msec (normal, n = 62 ) and QRS ≥ 120 msec (prolonged, n = 46 ). TWA (hazard ratio 2.2, P = 0.03 ) and QRS prolongation (hazard ratio 2.2, P = 0.01 ) were both significant and independent predictors of arrhythmic events. QRS prolongation had no effect on the prevalence of positive TWA tests ( QRS < 120 msec: 48%, QRS ≥ 120 msec: 50%, P = NS ). TWA was a highly significant predictor of events in patients with a normal QRS (hazard ratio 5.8, P = 0.02 ). In contrast, TWA was not useful for risk stratification in subjects with QRS prolongation (hazard ratio 1.1, P = 0.8 ). Conclusion: TWA is useful only for risk stratification in the absence of QRS prolongation. The presence of QRS prolongation and left ventricular ejection fraction ≤40% may be sufficient evidence of an adverse prognosis that additional risk stratification is not useful or necessary.