What is the clinical evidence from this study?

Study design: Observational. Population: Heart failure requiring cardiac resynchronization therapy (n=33). Intervention: Vectorcardiographic QRSarea and CMR myocardial scar quantification. Primary outcome: CRT response (≥15% reduction in left ventricular end-systolic volume).

February 7, 2018Open Access

Relationship between vectorcardiographic QRSarea, myocardial scar quantification, and response to cardiac resynchronization therapy

Key Result

A combined analysis of large vectorcardiographic QRSarea and small CMR focal scar predicted a 92% cardiac resynchronization therapy response rate.

Study Design

Type

Observational (n=33)

Structured PICO

Does combining vectorcardiographic QRSarea and CMR myocardial scar quantification improve prediction of response to cardiac resynchronization therapy in CRT patients?

Population

33 patients undergoing cardiac resynchronization therapy, evaluated with vectorcardiography and cardiac magnetic resonance imaging with 6 months of follow-up.

Exposure

Combined vectorcardiography (VCG) QRSarea and cardiac magnetic resonance (CMR) myocardial scar quantification (Scar2SD, Gray2SD)

Outcome

CRT response, defined as ≥15% reduction in left ventricular end-systolic volume after six months' follow-upsurrogate

Combining vectorcardiographic QRSarea with CMR-derived focal scar quantification provides incremental predictive value for identifying patients likely to respond to cardiac resynchronization therapy.

Abstract

To investigate the relationship between vectorcardiography (VCG) and myocardial scar on cardiac magnetic resonance (CMR) imaging, and whether combining these metrics may improve cardiac resynchronization therapy (CRT) response prediction. Thirty-three CRT patients were included. QRSarea, Tarea and QRSTarea were derived from the ECG-synthesized VCG. CMR parameters reflecting focal scar core (Scar2SD, Gray2SD) and diffuse fibrosis (pre-T1, extracellular volume ECV) were assessed. CRT response was defined as ≥15% reduction in left ventricular end-systolic volume after six months' follow-up. VCG QRSarea, Tarea and QRSTarea inversely correlated with focal scar (R = −0.44–−0.58 for Scar2SD, p ≤ 0.010), but not with diffuse fibrosis. Scar2SD, Gray2SD and QRSarea predicted CRT response with AUCs of 0.692 (p = 0.063), 0.759 (p = 0.012) and 0.737 (p = 0.022) respectively. A combined ROC-derived threshold for Scar2SD and QRSarea resulted in 92% CRT response rate for patients with large QRSarea and small Scar2SD or Gray2SD. QRSarea is inversely associated with focal scar on CMR. Incremental predictive value for CRT response is achieved by a combined CMR-QRSarea analysis.

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