Impact of Cardiac Resynchronization Therapy on Cardiac Electric Remodeling and its Clinical and Echocardiographic Correlation

Aim: impact of cardiac resynchronization therapy on cardiac electric remodeling and its clinical and echocardiographic correlation. Patients and Methods: 50 patients candidate for CRT were included and assessed before and 3 months after implantation by history taking, clinical examination, transthoracic echocardiogram, ECG and six minutes walk test. Results: 50 patients (35 males and 15 females, mean age 54.88±7.48 years) with implanted CRT. All patients were in sinus rhythm, QRS duration ≥120 ms and LBBB. There was clinical response to CRT as NYHA class improved p<0.001 and 6 min walk test p<0.001, electrocardiographic response where apart from RR interval, there were significant differences in QRSD, QT, QTc, QTd, and TPE between pre and post CRT measurements (P<0.001) and echocardiographic response as LV volume improved in 78%, EF in 14% and change (∆QRSD) significantly correlated with changes in NYHA, LVEDD, LVESD, and LVEF. (∆QTd) significantly correlated with change in NYHA but not with echocardiographic changes. But ( ∆TPE) significantly correlated with LVEDD, LVESD, LVEDV, LVESV, and LVEF but not with ∆NYHA. Area under the curve was 0.813 for ∆QRSD (p=0.005), 0.56 for ∆QT (p=0.56), 0.59 for ∆QTc (p=0.41), 0.823 for ∆QTd (p=0.004), and 0.8 for ∆TPE (p=0.007). ∆QTd of ≥-20 ms had highest sensitivity for predicting both clinical and Echocardiographic response, while ∆QRSD of ≥-20 ms had highest specificity. Conclusion: CRT induced reverse electric remodeling including depolarization and repolarization changes on unpaced ECG that was associated with reverse structural remodeling and clinical improvement.