Reverse electric remodeling after cardiac resynchronization therapy and relation to clinical and echocardiographic outcomes

BackgroundIn heart failure, there are structural and electric changes that affect the long term prognosis. While structural remodeling could be reversed by cardiac resynchronization therapy (CRT), little is known regarding reverse electric remodeling and its relation to the response to CRT.ObjectivesTo study the electric changes following CRT and their relation to patients’ response.MethodsThirty patients with implanted CRT device were included. Echocardiograms and surface electrocardiograms (ECGs) done before CRT were retrospectively analyzed. At the time of enrollment, echocardiography and ECG (during setting the CRT to off mode) were done. QRS duration (QRSD), QT interval, QTc interval, QT dispersion (QTd), and T wave peak to end (TPE) interval were measured.ResultsMean time since implantation was 15.26 ± 6 months. QRSD decreased from 146.33 ± 16.29 to 134.33 ± 17.15 ms (p < 0.001). QT interval decreased from 420.33 ± 28.46 to 398.66 ± 21.29 ms (p < 0.001). QTc interval decreased from 505.66 ± 45.53 to 475.23 ± 31.08 ms (p < 0.001). QTd decreased from 58 ± 13.23 to 34.66 ± 13.82 ms (p < 0.001). TPE interval decreased from 124 ± 24.3 to 102 ± 22.5 ms (p < 0.001). Responders to CRT (19 patients, 63.3%) had larger ΔQRSD, ΔQTd, and ΔTPE than non responders (p = 0.002, 0.002, and 0.004, respectively). Cutoff values of −20 ms for each of ΔQRSD, ΔQTd, and ΔTPE could predict response to CRT with odds ratio (95% CI) of 4.05 (1.12–14.6), 2.75 (1.25–6), and 4.43 (1.21–15.5), respectively.ConclusionsCRT induced reverse electric remodeling affecting both depolarization and repolarization parameters on surface ECG. Reverse electric remodeling was associated with favorable clinical and echocardiographic outcomes.