Decline in peak oxygen consumption over time predicts death or transplantation in adults with a Fontan circulation.

UNLABELLED

Peak oxygen consumption (pVO) measured by cardiopulmonary exercise test (CPET) predicts mortality in adults with a Fontan circulation. The purpose of this study was to assess the additive prognostic value of change in pVO over time.

METHODS

We analyzed a cohort of adults (≥18 years old) with a Fontan circulation who underwent at least 2 maximal CPETs separated by 6-30 months at Boston Children's Hospital between 2000 and 2015. Survival analysis was performed to determine whether changes in CPET variables, including pVO between consecutive tests, were associated with subsequent clinical events. The primary outcome was transplant-free survival.

RESULTS

The study included 130 patients with 287 CPET test pairs. Average age was 26.6±9.5 years. Baseline pVO averaged 22.0±5.7 mL/kg/min or 60.9%±13.7% predicted. In the cohort overall, there was no change in mean pVO between sequential CPETs. Eleven patients died and 2 underwent transplant. On average, pVO declined for patients who subsequently died or underwent transplant but remained stable among those who did not (-9.8%±14.6% vs 0.0±13.0%, P<.01). Those with a decline in pVO between CPETs were at greater risk of death or transplantation (per 10% decrease in pVO: HR=2.0, 95% CI 1.2-3.1, P=.004). Change in pVO remained a significant predictor of death or transplant after adjusting for pVO at first CPET (per 10% decline in pVO: HR=2.5, 95% CI 1.5-4.2, P<.001).

CONCLUSIONS

A decline in pVO between consecutive CPETs predicts increased risk for death or transplant in adults with a Fontan circulation independent of baseline pVO. These results support the additive clinical value of serial CPET in this population.