Cycle-length response of ventricular tachycardia associated with coronary artery disease to procainamide and amiodarone.
We undertook this study to determine if the cycle-length response of ventricular tachycardia (VT) to procainamide and amiodarone is similar in the individual patient. We enrolled 40 patients with uniform, monomorphic VT at a baseline, drug-free electrophysiologic study, after procainamide infusion and during oral amiodarone therapy. We found a significant correlation (p less than 0.01) between VT cycle-lengths on the 2 agents as well as the percent change in cycle length from baseline. Only 60% of the patients exhibited VT rates within 10% between the 2 agents. Importantly, less than 20% of patients had further slowing of the VT rate (greater than 10% slowing) during amiodarone therapy as compared to procainamide. Thus, although the cycle-length response of VT to procainamide correlates with the cycle-length response to amiodarone, 40% of patients have a disparate response (greater than 10% difference in cycle length) to the 2 agents; additional slowing of VT rates in response to amiodarone beyond that seen with procainamide is unlikely. These results have important implications regarding the institution of amiodarone therapy and the need for repeat electrophysiologic testing during amiodarone therapy.
Clinical Electrophysiology Laboratory, Hospital of the University of Pennsylvania, Philadelphia 19104.
P T
PT
Vaitkus
A E
AE
Buxton
M E
ME
Josephson
F E
FE
Marchlinski
D000638:Amiodarone / Q000627:therapeutic use*; D002304:Cardiac Pacing, Artificial; D003327:Coronary Disease / Q000150:complications*; D004594:Electrophysiology; D005260:Female; D006321:Heart / Q000187:drug effects / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011342:Procainamide / Q000627:therapeutic use*; D013610:Tachycardia / Q000188:drug therapy* / Q000209:etiology
D011342:Procainamide; D000638:Amiodarone