Background: The beneficial effects of cardiac resynchronization therapy (CRT) in heart failure are largely considered to be due to improved mechanical contractility. The contributory role of electrical remodelling is less clear. We sought to evaluate the impact of electrical remodelling in these patients.
Methods: 33 patients with conventional indications for CRT and with ischemic (ICM) (n = 17) and non-ischemic (NICM) (n = 16) aetiologies for heart failure were prospectively recruited. Functional parameters of peak exercise oxygen consumption (VO 2 max) and Minnesota quality of life (QOL) score, echocardiographic measures of LV functions and parameters of electrical remodelling, e.g. intrinsic QRS duration (iQRSD), intracardiac conduction times of LV pacing to RV electrocardiogram (LVp-RVegm), were measured at CRT implant and after 6 months.
Results: Only two electrical parameters predicted functional or symptomatic improvement. LVp-RVegm reduction significantly correlated with improvement in VO 2 max (r = −0.42, p = 0.03 while reduction in iQRSD significantly correlated with improvement in QOL score (r = 0.39, p = 0.04). The extent of changes in LVp-RVegm and iQRSD was significantly greater in NICM than in ICM patients (p = 0.017 and p = 0.042 for heterogeneity). There was also significant differential impact on QOL score in the NICM relative to the ICM group (p = 0.003) but none with VO 2 max. On multivariate analysis, only non-ischemic aetiology was a significant determinant of reduction in iQRSD.
Conclusion: CRT induces potentially beneficial reduction in LVp-RVegm and iQRSD, which are seen selectively in NICM rather than ICM patients. The extent of improvement in these markers is associated with some functional and symptomatic measures of CRT efficacy.
|Number of pages||8|
|Journal||JOURNAL OF ELECTROCARDIOLOGY|
|Early online date||4 Dec 2018|
|Publication status||Published - 1 Mar 2019|
- Cardiac resynchronization therapy
- Cardiopulmonary exercise testing
- Electrical remodelling
- Intracardiac conduction time
- Intracardiac electrocardiogram
- Intrinsic QRS duration