BACKGROUND: Adult patients with a small, unrepaired atrial septal defect (ASD) have higher mortality and increased risk of several comorbidities compared to general population. Further, reduced submaximal and peak exercise capacity was recently demonstrated in these patients. The mechanisms behind these findings remain unexplained and, therefore, biventricular contractility during exercise was assessed by evaluating the force-frequency relationship in the same group of patients.
METHODS: Adults patients with a small, unrepaired ASD and healthy age- and gender-matched controls were examined using echocardiography during supine bicycle exercise. Continuous tissue velocity Doppler was used to evaluate isovolumetric acceleration (IVA) and systolic velocities during an incremental workload protocol. All data were analyzed post hoc in a blinded fashion.
RESULTS: We included 30 patients previously diagnosed with a small, unrepaired ASD (mean age 35 years, 63% female) and 25 controls (mean age 34 years, 64% female). Patients had similar values of IVA and systolic velocities at rest when compared with the healthy controls. Further, no differences in IVA was found at peak heart rate for neither the left ventricle (90 ± 39 vs 129 ± 68 cm/s2 , P = 0.1547) nor the right ventricle (128 ± 56 vs 154 ± 56 cm/s2 , 0.5691). There were no correlations between peak velocities and the lower exercise capacity previously reported in these patients.
CONCLUSION: Adult patients with a small, unrepaired ASD have normal biventricular contractility at rest and during exercise when compared with healthy peers. Consequently, the pathophysiological mechanisms behind the impaired exercise capacity previously demonstrated in these patients remains unknown and will be a target for future work.