Larger spatial ventricular gradient magnitude is associated with higher rates of response to cardiac resynchronization therapy.

Background: Cardiac resynchronization therapy (CRT) improves systolic heart failure (HF) outcomes, but many patients do not benefit. Improved methods for identifying patients likely to benefit from CRT are needed. The spatial ventricular gradient (SVG) is a vectorcardiographic measure of myocardial electromechanical heterogeneity that is associated with incident HF. The relationship between SVG and CRT response is unknown. Objective: This study aimed to investigate associations between SVG and CRT response. Methods: Retrospective analysis of patients presenting for clinically-indicated CRT implant in 2015-2022. Pre-CRT electrocardiograms (ECGs) were transformed into vectorcardiograms (VCGs), and SVG vector X, Y, and Z components were calculated as areas under the X, Y and Z VCG QRST complexes, respectively. SVG magnitude (SVGmag) was calculated as SVG vector length. CRT response, defined as left ventricular ejection fraction (LVEF) increase ≥10% post-CRT, was assessed using multivariable logistic regression. Results: Among 162 patients (median age 68 years, 62% male, 76% non-ischemic HF, median LVEF 26%, median QRS duration 162ms, 89% left bundle branch block), 69% had CRT response. After adjustment, larger pre-CRT SVGmag was associated with higher odds of CRT response: adjusted odds ratio (ORadj) 1.78 per 1 standard deviation increase, P = .009. Predicted probabilities of CRT response ranged between ∼50% for the lowest SVGmag values, to ∼90% for the highest SVGmag values, and patients in the highest pre-CRT SVGmag tertile had and ORadj 4.5, P = .003 for CRT response. Larger post-CRT decreases in SVGmag were also associated with increased CRT response. SVGmag performed better than QRS area for predicting CRT response. Conclusion: SVGmag is independently associated with CRT response and warrants prospective study.