Relationship between J Waves and Vagal Activity in Patients Who Do Not Have Structural Heart Disease.

Abstract

Jwaves are associated with increased vagal activity in patients with idiopathic ventricular fibrillation in several studies to date. However, the relationship between Jwaves and autonomic nervous activity in patients without structural heart disease remains under investigation. We investigated whether the presence of a Jwave on the surface electrocardiogram (ECG) was related to increased vagal activity in patients without structural heart disease. This retrospective study included 684 patients without structural heart disease who had undergone Holter ECG and surface ECG monitoring. Based on the presence of Jwaves on the surface ECG, patients were divided into two groups: those with Jwaves (group 1) and those without Jwaves (group 2). We compared heart rate variability (HRV), reflecting autonomic nervous activity, using 24-h Holter ECG between the groups. Jwaves were present in 92 (13.4%) patients. Heart rate (HR) in group 1 was significantly lesser than that in group 2 (P = 0.031). The ratio of low-frequency (LF) components to high-frequency (HF) components (LF/HF) in group 1 was significantly lower than that in group 2 (P = 0.001). The square root of the mean squared differences of successive NN intervals in group 1 was also significantly higher than that in group 2 (P = 0.047). In a multivariate regression analysis, male sex, HR, and LF/HF ratio remained independent determinants for the presence of Jwaves (P = 0.039, P = 0.036, and P < 0.001, respectively). In patients without structural heart disease, the presence of a Jwave was associated with a slow HR, male sex, and increased vagal activity, independently.