title: Warm-up phenomenon and cardiac autonomic control in patients with coronary artery disease.
abstract: Decreased heart rate variability (HRV) and heart rate turbulence (HRT) are independent predictors of mortality after acute myocardial infarction (AMI). There are no previous studies on the relationship between warm-up phenomenon and cardiac autonomic control in stable coronary artery disease (CAD). We investigated the responses in HRV to repeated exercise induced ischemia and differences in global HRV and HRT in patients with and without adaptation to ischemia (warm-up phenomenon). Fifty male patients with CAD underwent two successive exercise tests with ambulatory electrocardiogram (ECG) recordings. HRV was evaluated using time and frequency domain measures and HRT was determined among patients with ventricular premature complexes (VPCs). The patients were divided in two groups on the basis of either positive (warm-up+) or negative (warm-up-) ischemia adaptation. Total power, ULF and VLF power and pNN50 calculated from the entire ECG recording were higher in the group demonstrating warm-up phenomenon (P<0.05 for all). In the assessment of the four short-term stationary phases (pre-and post-test 1 and 2) total power, VLF power and pNN50 were significantly higher in the warm-up positive group already at the baseline (P<0.05 for all). Furthermore, in the entire recordings total power, ULF and VLF power and SDNN correlated positively with the decrease in ischemic burden in the recovery phase (P<or=0.001 for all). No significant differences were found in HRT between the groups. Our results suggest that CAD patients demonstrating warm-up phenomenon have better cardiac autonomic control, and this correlates with the extent of ischemia adaptation. The true prognostic significance of this needs to be prospectively studied, however.
authors.affiliation: Department of Internal Medicine, Kuopio University Hospital, P.O. Box 1777, 70211 Kuopio, Finland. Petri.Tuomainen@kuh.fi
authors.forename: Petri
authors.initials: P
authors.lastname: Tuomainen
authors.forename: Juha
authors.initials: J
authors.lastname: Hartikainen
authors.forename: Esko
authors.initials: E
authors.lastname: Vanninen
authors.forename: Keijo
authors.initials: K
authors.lastname: Peuhkurinen
mesh_terms: D000368:Aged; D001341:Autonomic Nervous System / Q000503:physiopathology*; D006328:Cardiac Catheterization; D003324:Coronary Artery Disease / Q000503:physiopathology*; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018879:Ventricular Premature Complexes / Q000503:physiopathology