RESUMO
OBJECTIVE: Cardiac resynchronization therapy (CRT) is an effective option in the treatment of patients with heart failure and wide QRS. Presence of fragmented QRS (f-QRS) on 12-lead electrocardiogram (ECG) has been shown to be associated with non-response to CRT. The aim of this study was to evaluate whether onset of fragmentation (Q-f interval) is important for CRT response. METHODS: This is a single-center retrospective analysis of prospectively collected data of 38 non-ischemic dilated cardiomyopathy patients (18 men, mean age 63±12 years) with f-QRS on 12-lead ECG who underwent CRT. Duration of fragmentation, ratio of f-QRS duration to the total QRS duration (f-QRS/t-QRS ratio) and time interval from Q wave to the onset of QRS fragmentation (Q-f interval) were measured. RESULTS: The baseline clinical, echocardiographic findings of patients with responders (24 patients, 63%) and non-responders showed no statistically significant difference, except for longer f-QRS duration, increased ratio of f-QRS duration to the total QRS duration (f-QRS/t-QRS ratio) and shorter time interval from Q wave to the onset of QRS fragmentation (Q-f interval) in patients not responding to CRT. In multivariate analysis, Q-f interval was determined as an independent predictor of response to CRT (OR 1.240, 95% CI: 1.049-1.467, P=.012). In ROC curve analysis, the best cut-off value for Q-f interval to predict responders was 32.5ms with a sensitivity and specificity of 83.3% and 85.7%, respectively (AUC 0.899, 95% CI: 0.797-1.000, P=.001). CONCLUSIONS: Shorter time from onset of QRS to beginning of fragmentation is a simple ECG marker to predict non-responsive patients to CRT.
