Fontan Failure: Are Changes In Paced Qrs Duration Over Time Associated With Worse Disease?

Background/Methods: Fontan failure is a diverse phenotype describing pathology in multiple organ systems that occurs in congenital heart disease (CHD) patients with a functionally univentricular heart who have undergone surgical Fontan. While many Fontan patients receive permanent pacemakers (PPMs) to manage arrhythmias, having a pacemaker is also associated with poor outcomes in selected patients, including Fontan failure and death. There is some evidence that increased QRS duration (QRSd) may be associated with poor cardiac function and clinical outcomes. We investigated whether paced QRSd changes over time in Fontan patients and whether prolongation of paced QRSd is associated with Fontan failure. Results: We identified 25 Fontan patients with PPMs: 11 Fontan patients with a substantial ventricular pacing burden (group 1; ≥15% ventricular pacing) and 14 Fontan patients with minimal or no ventricular pacing (group 2; \u3c15% ventricular pacing) for an average follow-up time of 6.8 and 10.9 years, respectively. The increase in paced QRSd over the follow-up period was not significantly different between groups 1 and 2 (19 vs 7 ms, p=0.13). A substantially higher proportion of patients in group 1 developed Fontan failure compared to patients in group 2 (64% vs 7%, p=0.007). Within group 1, patients who developed Fontan failure (n=7) had significantly longer QRSd at initial paced ECG (172 vs 135 ms, p=0.03) and at last follow-up (198 vs 140 ms, p=0.03) compared to those without Fontan failure (n=4). Patients with Fontan failure also had a notably greater increase in QRSd over time compared to healthy Fontan patients, though this difference was not statistically significant (26 vs 6 ms, p=0.07). Conclusions/Future Directions: Further study with larger populations would be helpful to better elucidate the relationship between pacing and Fontan failure. Multisite ventricular pacing, minimization of ventricular pacing burden, and other management strategies merit further study of their potential benefits for these complex patients