High life inadvisable after Fontan procedure
medwireNews: Living at even a moderate altitude may have an adverse impact on the health and survival of patients who have undergone the Fontan procedure for single-ventricle anatomy, say researchers.
The patients in the study lived at a moderate altitude, and were treated at a center in the Intermountain West (elevation 5000 feet) region of the USA. During follow up, patients who died or needed a transplant lived at a higher altitude than those who did not (4637 vs 4296 feet).
Moreover, the cohort as a whole had poorer survival than previously described cohorts living at sea level, report Anji Yetman (University of Utah, Salt Lake City, USA) and team.
"The reduction in survival is not particularly surprising if one considers the physiological adaptations to increased elevation present at moderate altitude," they write in the Journal of the American College of Cardiology. "The rise in pulmonary vascular resistance will lead to impedance to forward flow through the Fontan circuit, predisposing to Fontan failure, hepatic congestion, and PLE [protein-losing enteropathy]."
PLE occurred in 19 (26.7%) of the 103 patients in the current study, who underwent the Fontan procedure between 1978 and 2005. Again, PLE was more frequent than reported in sea-level cohorts. Just three patients with PLE survived to the time of follow up, and of these survivors, one was being evaluated for transplantation and another was in hospice care.
All other patients with PLE died of thrombembolic events, and thrombotic events occurred in 49% of the whole cohort. On multivariate analysis, PLE was associated with a sevenfold increase in the risk for an adverse outcome (death, cardiac transplantation, or clinical decompensation that required a move to sea level), and thrombosis raised the risk 3.6-fold.
"Given the very high rate of thromboembolism in our patient cohort… consideration may need to be given to a multicenter study of primary thromboprophylaxis of Fontan patients living at moderate or greater altitude," say Yetman et al.
In all, 24 patients died, 18 needed cardiac transplantation, and 13 had to move to sea level for medical reasons. In the multivariate analysis, each 100-foot increase in residential altitude was associated with an 8.4% rise in risk for an adverse outcome. Higher pre-Fontan pulmonary artery pressure and lower oxygen saturation were also associated with adverse outcomes.
"The effect of relocation to lower elevation remains unknown but is deserving of future study," say the researchers. "Presence of these other risk factors should prompt consideration of transplantation or a trial of living at sea level."
By Eleanor McDermid, Senior medwireNews Reporter