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Elevated myocardial extracellular volume fraction is associated with the development of conduction pathway defects
Rafey Feroze1, Puneet Kang2, Luis Augusto Palma Dallan1
1Division of Cardiology, Harrington Heart and Vascular Institute, University Hospitals Cleveland Medical Center, Cleveland, Ohio, USA.
Insights
Myocardial fibrosis measured by extracellular volume (ECV) is linked to conduction problems after transcatheter aortic valve replacement (TAVR). Elevated ECV may help identify patients needing closer monitoring or a pacemaker post-TAVR.
Area of Science:
- Cardiology
- Medical Imaging
- Interventional Cardiology
Background:
- Transcatheter aortic valve replacement (TAVR) is a common treatment for aortic stenosis.
- TAVR carries risks, including heart block and pacemaker dependency.
- Current methods for predicting heart block risk after TAVR are imperfect.
Purpose of the Study:
- To investigate the association between myocardial fibrosis, assessed by cardiac magnetic resonance imaging (CMR), and new conduction abnormalities after TAVR.
- To determine if late gadolinium enhancement (LGE) and extracellular volume (ECV) measurements from CMR can predict post-TAVR conduction disturbances.
Main Methods:
- Retrospective review of 170 patients who underwent CMR before TAVR.
- Measurement of septal LGE (replacement fibrosis) and ECV (interstitial fibrosis).
- Analysis of new conduction abnormalities, including atrioventricular block, bundle branch blocks, and pacemaker requirement.
Main Results:
- 27.1% of patients developed post-TAVR conduction deficits.
- Higher ECV values were significantly associated with new conduction defects (p=0.020).
- An ECV of ≥26% independently predicted new conduction defects (OR: 2.364, p=0.030) and showed a strong association in ROC analysis (AUC: 0.632).
- Combining prior right bundle branch block (RBBB) with ECV improved prediction (AUC: 0.779).
- ECV was independently associated with conduction deficits in patients without baseline conduction disease (OR: 3.685, p=0.008).
Conclusions:
- Interstitial myocardial fibrosis, indicated by ECV, is associated with new conduction abnormalities following TAVR.
- ECV shows potential as a novel risk stratification tool for identifying patients at higher risk of post-TAVR conduction disturbances.
- ECV may aid in selecting patients for closer surveillance or pacemaker implantation after TAVR.
Background:
Transcatheter aortic valve replacement (TAVR) has become an established method of aortic stenosis treatment but suffers from the risk of heart block and pacemaker requirement. Risk stratification for patients who may develop heart block remains imperfect. Simultaneously, myocardial fibrosis as measured by cardiac magnetic resonance imaging (CMR) has been demonstrated as a prognostic indicator of ventricular recovery and mortality following TAVR. However, the association of CMR-based measures of myocardial fibrosis with post-TAVR conduction disturbances has not yet been explored.
Aims:
We evaluated whether myocardial fibrosis, as measured by late gadolinium enhancement and extracellular volume (ECV) from CMR would be associated with new conduction abnormalities following TAVR.
Methods:
One hundred seventy patients who underwent CMR within 2 months before TAVR were retrospectively reviewed. Septal late gadolinium enhancement (LGE) and ECV measurements were made as surrogates for replacement and interstitial fibrosis respectively. New conduction abnormalities were defined by the presence of transient or permanent atrioventricular block, new bundle branch blocks, and need for permanent pacemaker. Association of myocardial fibrosis and new conduction derangements were tested using receiver operator curve (ROC) and regression analysis in patients with and without pre-existing conduction issues.
Results:
Forty-six (27.1%) patients developed post-TAVR conduction deficits. ECV was significantly higher among patients who experienced new conduction defects (26.2 ± 3.45% vs. 24.7% ± 4.15%, p value: 0.020). A greater fraction of patients that had new conduction defects had an elevated ECV of ≥26% (54.3% vs. 36.3%, p value: 0.026). ECV ≥ 26% was independently associated with the development of new conduction defects (odds ratio [OR]: 2.364, p value: 0.030). ROC analysis revealed a significant association of ECV with new conduction defects with an area under the receiver operating characteristic curve (AUC) of 0.632 (95% confidence interval: 0.555-0.705, p value: 0.005). The combination of prior right bundle branch block (RBBB) and ECV revealed a greater AUC of 0.779 (0.709-0.839, p value: <0.001) than RBBB alone (Delong p value: 0.049). No association of LGE/ECV with new conduction defects was observed among patients with pre-existing conduction disease. Among patients without baseline conduction disease, ECV was independently associated with the development of new conduction deficits (OR: 3.685, p value: 0.008).
Conclusion:
The present study explored the association of myocardial fibrosis, as measured by LGE and ECV with conduction deficits post-TAVR. Our results demonstrate an association of ECV, and thereby interstitial myocardial fibrosis, with new conduction derangement post-TAVR and introduce ECV as a potentially new risk stratification tool to identify patients at higher risk for needing post-TAVR surveillance and/or permanent pacemaker.
