QRS Complex Duration and Area as Indicators of Response to Cardiac Resynchronization Therapy (CRT)

Heart failure (HF) is a complex disorder that often results in electrical dyssynchrony, indicated by a widened QRS complex. Cardiac resynchronization therapy (CRT) improves ventricular synchronization and function. This study aims to compare QRS complex duration and area in post-three-chamber pacing HF patients who experienced significant symptom relief and those who did not see any improvement to enhance understanding of CRT outcomes.

This study was conducted in the Rajaie Heart Center, which included 203 HF patients with left bundle branch block (LBBB) (QRS duration ≥ 120 ms, left ventricular ejection fraction (LVEF) ≤ 35%). Data were collected from electronic medical records, focusing on QRS duration and area pre- and post-CRT implantation. Statistical analysis utilized International Business Machines-Statistical package for the social sciences (IBM SPSS) Statistics 27.0, with a significance set at p < 0.05.

This study evaluated 203 HF patients who underwent CRT. The average age of participants was 65.6 years, with 43.6% diagnosed with ischemic cardiomyopathy. The post-CRT QRS duration in lead V5 demonstrated a statistically significant difference (p = 0.015), suggesting potential improvement in the symptom improvement group. Additionally, while the post-CRT QRS complex area (QRS area) in lead V5 showed notable differences between the two groups (p = 0.069), the QRS duration and area in lead V5 were significantly lower in the group that experienced symptom improvement.

In conclusion, the post-CRT QRS duration and area significantly decreased in lead V5 patients who experienced symptom improvement. In contrast, other leads did not demonstrate statistical significance. This suggests that the effects of CRT on the ECG may vary, indicating the need for further studies with larger sample sizes to validate these findings.