Aims: High resting heart rate (HR) has been associated with sudden cardiac death (SCD). This association is not fully explained by the reported association between HR with coronary heart disease (CHD) or left ventricular systolic dysfunction, the major pathological substrates for SCD. Ventricular arrhythmia is the most common antecedent event before SCD. Examining associations between resting HR and ventricular arrhythmogenesis may enhance our understanding of the association between high resting HR and SCD.
Methods and results: This study included 867 patients (age 54 +/- 5, 57% females) who underwent 24 h ambulatory electrocardiographic (ECG) recording (Holter) in the period from 1998 to 2000. We examined the unadjusted and multivariable-adjusted associations between resting HR with factors involved in ventricular arrhythmogenesis [ventricular late potentials (LPs) detected by signal-averaged ECG, heart rate variability (HRV), and premature ventricular complexes (PVCs)]. Linear regression models were used for continuous outcomes and logistic regression analysis was used for categorical outcomes. The multivariable models included first age and sex, then history of hypertension, diabetes, hypercholesterolaemia, CHD, heart failure, left ventricular ejection fraction (LVEF), smoking, body mass index, the use of anti-arrhythmic drugs, and ST-depression in the 24 h ambulatory ECG recording (Holter) were included in the final models. In the unadjusted and multivariable-adjusted analysis, high resting HR was significantly associated with positive ventricular LPs, depressed HRV indices, and increased prevalence of PVCs/24 h independently from demographic and clinical variables including LVEF, history of CHD, and the presence of ST-depression in Holter (P-value <0.05 in all comparisons and models).
Conclusion: High resting HR is independently associated with ventricular arrhythmogenesis, the major cause of SCD. These findings could partially explain the reported association between increased HR and SCD.