Abstract 9473: Prognostic Significance of Temporal Increase in QRS Duration and Morphological Development of QRS Complex

Background: QRS duration and morphology provide an opportunity to derive useful prognostic information. But, prognostic value of temporal increase in QRS duration in relation to the morphological development is yet to be determined. Methods: From among a database containing 359,737 ECGs, digital analysis of 12-lead ECG was performed to select patients whose QRS duration increased from <110 ms to ≥120 ms over time. The long-term prognosis was assessed according to QRS morphology. Hospitalization for heart failure was the primary end point, and the cardiovascular composite events of hospitalization for heart failure, device implantation, or cardiovascular death were the secondary end point. Results: We enrolled 143 patients (100 males; mean age, 58.9±11.1 years). During follow-up (mean, 12.0±5.3 years), QRS duration increased by 46.4±13.8 ms (49.6%), resulting in the development of right bundle branch block (RBBB) in 99 (69.2%) patients and non-RBBB (i.e., left bundle branch block,RBBB with left anterior hemiblock, or intraventricular conduction disturbance) in 44 (30.8%) patients. During a mean follow-up of 16.6±5.3 years, 44(30.3%),15(10.3%), and 6(4.1%) patients resulted in heart failure hospitalization,device implantation, and cardiovascular death, respectively. Cox proportional -hazards model showed that 1) the temporal increment of QRS duration was significantly associated with the primary end point (HR 1.98; 95% CI 1.05-3.80; P=0.04 for QRS duration ≥4 ms/year versus <4 ms/year) and the secondary end point (HR 2.79;95% CI 1.55-5.00; P=0.0001 for QRS duration ≥5 ms/year versus <5 ms/year),2) QRS morphology was significantly associated with the primary end point (HR 3.02;95% CI 1.59-5.73; P=0.0001 for non-RBBB versus RBBB) and the secondary end point (HR 2.82; 95% CI 1.57-3.09; P=0.001 for non-RBBB versus RBBB), and 3) the temporal increment of QRS duration and the QRS morphology of non-RBBB potentiated each other, leading to the higher primary end point rate (HR 7.73; 95% CI 2.90-22.74;P<0.0001) and the higher secondary end point rate (HR 8.25; 95% CI 3.39-19.85; P<0.0001). Conclusion: Newly developed wide QRS complex excluding RBBB played a significant role in heart failure hospitalization and cardiovascular events.