Heart rate dynamics at the onset of ventricular tachyarrhythmias as retrieved from implantable cardioverter-defibrillators in patients with coronary artery disease

Background-The recent availability of implantable cardioverter-defibrillato rs (ICDs) that record 1024 R-R intervals preceding a ventricular tachyarrhy thmia (VTA) provides a unique opportunity to analyze heart rate variability (HRV) before the onset of VTA. Methods and Results-Fifty-eight post-myocardial infarction patients with an implanted ICD for recurrent VTA provided 2 sets of 98 heart rate recording s in sinus rhythm: (1) before a VTA and (2) during control conditions. Thre e subgroups were considered according to the antiarrhythmic (AA) drug regim en. A state of sympathoexcitation was suggested by the significant reductio n in HRV before VTA onset compared with control conditions. beta-Blockers a nd dl-sotalol enhanced HRV in control recordings; nevertheless, HRV decline d before VTA independent of AA drugs. A gradual increase in heart rate and decrease in sinus arrhythmia at VTA onset were specific findings of patient s who received dl-sotalol. Conclusions-The peculiar heart rate dynamics observed before VTA onset are suggestive of a state of sympathoexcitation that is independent of AA drugs .