AVV Regurgitation Post-Fontan Associated With Higher Mortality, Transplantation Risk Only in RV-Dominant Patients

Moderate or high atrioventricular valve (AVV) regurgitation after a Fontan procedure may be associated with a greater risk of mortality or transplantation, but only in patients with right ventricular (RV) dominance, according to a study published in the Journal of the American College of Cardiology and presented April 4 at ACC.22.

Gregory King, MD, et al., used data from the Australia and New Zealand Fontan Registry to look at the effect of RV dominance on outcomes after a Fontan procedure, with the goal of determining whether successful AVV surgery would modify AVV incompetence among RV-dominant patients. The study's primary outcome was death or heart transplantation, and the secondary outcome was the cumulative incidence of ≥moderate AVV regurgitation post-Fontan. The researchers used propensity score matching to assess the impact of AVV operation on outcomes before Fontan or at completion.

The final cohort consisted of 1,703 patients who had a Fontan procedure in Australia or New Zealand, or who were followed up in the region, from 1987 to 2021. A sensitivity analysis was performed only on patients who received the procedure since 2000. Of all patients, 126 (7%) died without transplantation and 38 (2%) underwent heart transplantation.

In the unmatched cohort, there was a significantly higher cumulative incidence of death or transplantation 20 years after the Fontan procedure in patients undergoing AVV surgery before or at Fontan completion. After propensity-matching, there was no significant difference in death or transplantation after 20 years (18% for those receiving AVV surgery vs. 16% for those who did not), except in patients with RV dominance.

The cumulative incidence of ≥moderate AVV regurgitation 10 and 20 years after the Fontan procedure was 10% and 18%, respectively. Among all patients, 174 (10%) had at least one AVV operation before or at Fontan completion. Patients who underwent an AVV operation were more likely to have RV dominance (48% vs. 33%; p<0.01), an atrioventricular septal defect (20% vs. 9%; p<0.01), aortic atresia (15% vs. 6%, p<0.01), and to be older when undergoing the Fontan procedure.

The 20-year cumulative incidence of death or transplantation was 37% among patients who developed ≥moderate AVV regurgitation after Fontan vs. 13% in patients with <moderate AVV regurgitation. In patients with RV dominance who developed ≥moderate AVV regurgitation, the risk of death or transplantation was higher compared to patients with <moderate AVV regurgitation (Hazard Ratio: 2.8; 95% Confidence Interval: 1.4-5.3; p<0.01).

According to the researchers, baseline characteristics, particularly RV dominance, has a "much greater impact on the rate of death or transplantation in those who underwent AVV operation than the AVV operation itself." They conclude that ≥moderate AVV regurgitation at any time after a Fontan procedure significantly increases the risk of mortality or transplantation, but only in patients with RV dominance.

In a related editorial comment, Adam L. Dorfman, MD, FACC, and Pedro J. del Nido, MD, write that the study's conclusion "is supported by other studies analyzing the response of the RV to systemic loading conditions." They conclude that it "remains to be seen" whether early AVV surgery for post-Fontan patients with RV dominance "proves to be a successful strategy for improving outcomes … and is a crucial topic for future study."

Keywords: ACC Annual Scientific Session, ACC22, Fontan Procedure, New Zealand, Propensity Score, Heart Transplantation, Aortic Diseases, Australia, Registries, Heart Septal Defects, Reoperation

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