QRS area as a predictor of cardiac resynchronization therapy response: A systematic review and meta-analysis

QRS area, a three-dimensional QRS complex, is a novel vectorcardiography method of measuring the magnitude of electrical forces in the heart. Hypothetically, a greater QRS area denotes higher dyssynchrony and indicates potential benefits from cardiac resynchronization therapy (CRT). Previous studies suggest a positive correlation between QRS area and the degree of response to CRT, but its clinical use remains unclear. We performed a meta-analysis of the relationship between QRS area and survival benefit following CRT.

We comprehensively searched the MEDLINE, EMBASE, and Cochrane databases from inception to August 2021. We included studies with prospective and retrospective cohort designs that reported QRS area before CRT and total mortality. Data from each study were analyzed using a random-effects model. The results were reported as a hazard ratio (HR) and 95% confidence intervals.

Five observational studies including 4931 patients were identified. The cut-off values between large and small QRS areas ranged from 102 to 116 μVs. Our analysis showed a larger QRS area was statistically associated with increased 5-year survival in patients implanted with CRT (HR pooled 0.48, 95% CI 0.46-0.51, I²  = 54%, p < .0001). Greater QRS area reduction (pre- and post-implantation) were associated with a lower total mortality rate (HR pooled 0.45, 95% CI 0.38-0.52, I²  = 0%, p < .0001).

Larger pre-implantation QRS area was associated with increased survival after CRT. QRS area reduction following CRT implantation was also associated with lower mortality. QRS area may potentially become an additional selection criterion for CRT implantations.