Abstract 4147858: ECG correlates of chronic right ventricular pacing: QT interval predicts pacing-induced cardiomyopathy while QRS duration predicts cardiac resynchronization therapy response

Background: Some patients with chronic right ventricular (RV) pacing develop pacing-induced cardiomyopathy (PICM) and benefit from upgrade to cardiac resynchronization therapy (CRT). However, there are no established ECG screening criteria for PICM. Aim: We sought to evaluate ECG correlates of (i) PICM and (ii) CRT response. Methods: We retrospectively identified all CRT upgrades (biventricular pacing) for PICM (LVEF <50%) at our center 2014-2018 and gauged CRT response (LVEF increase >5% on echocardiogram 3-12 months post CRT). Patients with ≥5 ECGs all demonstrating RV pacing over ≥2 years and all echocardiographic LVEF ≥50% served as controls. Root-mean-squared (3D) ECG was obtained from reconstructed orthogonal X, Y, Z leads. We used logistic regressions to predict PICM and CRT response from ECG intervals and voltage-time-integrals (VTI). Results: 108 patients [74±11 years, 28% female, LVEF 29±8%, QRS duration (QRSd) 167±25 ms, QTc 515±39 ms] with CRT upgrade for PICM were compared to 186 controls (77±14 years, 53% female, LVEF 57±5%, QRSd 144±21 ms, QTc 473±33 ms). Discrimination of PICM was highest with QTc (AUC 0.80) followed by QRSd (0.77) and VTI QRS-3D (0.75, Table 1, Figure 1 ). QTc >480 ms detected PICM with sensitivity 84% and specificity 74%. With CRT upgrade , LVEF improved by 14±11%. CRT response (ΔLVEF >5%) occurred in 77/108 (71%). Lack of CRT response was best predicted by QRSd (AUC 0.65) followed by ΔVTI QRS-3D (0.61, Table 2 ). Lack of CRT response was noted in 52% with QRSd >180 ms, while 78% with QRS duration ≤180 ms showed CRT response. Conclusions: In patients with chronic RV pacing, QTc >480 ms identifies those susceptible to PICM, and QRSd >180 ms identifies those who may not respond to CRT.