Abstract 2651: Clinical Significance of Early Heart Rate Recovery After Exercise Testing in Patients With Brugada Syndrome
Backgrounds: Early heart rate recovery (HRR) after exercise is considered to be predominantly due to parasympathetic reactivation. Parasympathetic activation relates to augmentation of ST-segment elevation and occurrence of ventricular fibrillation (VF) in patients with Brugada syndrome (BrS). We reported augmentation of ST-segment elevation at early recovery phase after exercise testing was a prognostic factor in BrS patients. The aim of this study is to evaluate the relationship between parasympathetic reactivation and augmentation of ST-segment elevation at early recovery phase by using HRR.
Methods: Seventy-two patients (all men, 45.2±12.9 years) with BrS underwent treadmill exercise testing, and the response of ST-segment elevation in precordial leads and HRR were analyzed. HRR was defined as heart rate decrease in the first minute after peak exercise cessation. The patients were followed up during 74. ±41 months.
Results: Augmentation of ST-segment elevation (≥0.05mV) at early (1–4 minutes) recovery phase compared to baseline was observed in 30 patients (42%). HRR was significantly correlated with degree of ST augmentation at early recovery phase (3 minutes after exercise cessation, Regression coefficient [R] =0.41, P<0.001). By Cox regression, ST augmentation was significantly correlated with subsequent occurrence of VF (HR=2.05, P=0.007), although HRR was not. In subgroup analysis for 19 patients with VF occurrence during follow-up period, there was no correlation between HRR and ST augmentation, while 53 patients without VF occurrence showed significant correlation between HRR and ST augmentation (R=0.48, P<0.001).
Conclusions: Our data suggest that augmentation of ST-segment elevation at early recovery phase after exercise testing was induced by unknown factor other than HRR (parasympathetic reactivation) in BrS patients with VF occurrence. HRR could not predict poor prognosis of BrS patients.