Exercise-capacity decline hastened by congenital heart disease



ROME – Young adults with congenital heart disease lose roughly 1% of their predicted exercise capacity each year, based on follow-up of more than 500 patients at one German center.

The "slow but persistent decline" in patients with congenital heart disease "exceeds the decline of reference values for age" compiled in 2009 from the general German population, Jan Müller, Ph.D., said at the annual meeting of the European Association for Cardiovascular Prevention and Rehabilitation*.

Results from prior, smaller studies also showed greater-than-expected progressive loss of exercise capacity in adults with congenital heart disease, but those had been smaller studies, and had not involved as diversified a range of congenital heart diseases as the new study. The 522 patients reviewed by Dr. Müller and his associates included 29% with pulmonary valve dysfunction and 26% with a left-ventricular outflow obstruction, congenital defects not previously covered in longitudinal reports on exercise capacity, said Dr. Müller, a researcher in sports science at the German Heart Center in Munich.

"We don’t know whether the rate of decline is prognostic, but we know that patients with lower exercise capacity have worse outcomes," he said in an interview. He also believes that these patients would benefit from a training-program intervention, but that has not yet been proven in a study.

Dr. Müller and his associates reviewed records from more than 5,000 cardiopulmonary exercise tests done on patients with congenital heart disease at the Heart Center between July 2001 and August 2012. The series included 522 patients who had serial, validated tests run at least 6 months apart and who did not undergo any medical or surgical intervention during the inter-test period. The average interval between the initial and subsequent test was about 2.5 years. The patients averaged about 25 years of age at baseline and about 27 years old at the time of their second test, and 59% were men.

The next most common congenital disorder following pulmonary valve dysfunction and left-ventricular outflow obstruction was need for arterial switch or congenitally corrected transposition of the great arteries, in 18%, followed by Fontan circulation in 11%, Epstein’s anomaly in 8%, and less common defects in the remaining patients.

Although the group overall lost an average of about 1% of their predicted peak oxygen uptake per year during follow-up, the rate of loss varied substantially by type of congenital defect. Patients with Epstein’s anomaly lost an average of 1.54% of predicted annually, those with a left-ventricular outflow obstruction averaged a 1.28% decline from predicted per year, and patients with pulmonary valve dysfunction averaged a 1.12% loss per year. Patients with lower than average annual loses included those with an arterial switch or transposition, with an average 0.67% loss per year, and patients with Fontan circulation, with an annual loss that averaged only 0.02%. Because exercise capacities were calculated as a percent of predicted values, they included adjustment for age, sex, weight, and height.

The analysis also showed other statistically significant functional declines in the entire group during follow-up, including an average annual fall of 0.76% in peak oxygen delivery per heartbeat, and a 1.49-beat/min decline in peak heart rate.

The rate of decline in exercise capacity was about the same regardless of patient age. And in a multivariate analysis, patients with a pacemaker were significantly more likely to have a larger average annual decline in exercise capacity, he said.

Dr. Müller said that he had no disclosures.

On Twitter @mitchelzoler

*Correction, 5/29/2013: An earlier version of this story misstated the meeting name.

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