Heart rate variability is impaired in adults after closure of ventricular septal defect in childhood: A novel finding associated with right bundle branch block.

BACKGROUND: Ventricular septal defects (VSDs) generally have benign long-term prognoses, but recent studies have indicated increased pulmonary vascular resistance. A potential tool for monitoring pulmonary artery pressure is heart rate variability, and therefore, the aim of this study was to assess heart rate variability in adults with a surgically repaired or unrepaired VSD.

METHODS: In a long-term, follow-up study, three groups were included; VSD-patients operated in early childhood, patients with an open VSD, and controls. For each patient, 24-hour Holter monitoring was performed and heart rate variability was assessed.

RESULTS: In total, 30 participants with a surgically closed VSD, 30 participants with an unrepaired VSD, and 36 controls were included. In the closed VSD group, there was a higher proportion of participants, who had low sNN50 (p = 0.005) and low sNN6% (p = 0.017) than in the other two groups. Similar differences were found when sNN50 was divided into increases and decreases (p = 0.007 and p = 0.005, respectively) as well as sNN6% (p = 0.014 and p = 0.014, respectively). Lastly, there was a higher proportion of patients in the closed VSD group with low rMSSD than in the other two groups (p = 0.005). For the closed VSD group, the proportion of participants with low total sNN50 (p = 0.046) and low total sNN6% (p = 0.046) were higher among participants with a complete right bundle branch block (RBBB) than among participants with no or an incomplete RBBB.

CONCLUSIONS: Adults who had surgical VSD closure in early childhood had impaired heart rate variability and, particularly, participants with complete RBBB had lower heart rate variability.