Clinical and electrocardiographic characteristics of responders and nonresponders to class IA antiarrhythmic drugs.
A retrospective analysis of 44 patients was carried out to evaluate the efficacy of class IA antiarrhythmic drugs (disopyramide and/or procainamide), and of drugs of one or more other classes by means of 24-hour Holter recording. This study included only patients who exhibited 5000 or more ventricular premature complexes (VPCs) during a 24-hour pretrial baseline recording. The drugs that reduced the frequency of VPCs by at least 50% were considered effective. Eighteen patients (41%) responded to class IA drugs (responders) and 26 patients (59%) did not (nonresponders). There was a significant difference between the two groups in relation to the types of disease (p less than 0.01), but no significant difference with regard to other clinical and electrocardiographic characteristics. There was a significant discordance between trials of class IA drugs and class IC drugs (p less than 0.05). The efficacy of class IA drugs is very similar to that of class IB drugs, and only class IC drugs represent the highest efficacy in patients refractory to both class IA and class IB drugs. In conclusion, when ventricular arrhythmias do not respond to class IA or IB drugs, class IC drugs could be chosen as the next regimen.
Atarashi
H
H
First Department of Internal Medicine, Nippon Medical School, Tokyo, Japan.
Kawaguchi
N
N
Gotoh
M
M
Hayakawa
H
H
D000328:Adult; D000889:Anti-Arrhythmia Agents / Q000145:classification* / Q000627:therapeutic use; D001145:Arrhythmias, Cardiac / Q000188:drug therapy* / Q000503:physiopathology; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D012189:Retrospective Studies
D000889:Anti-Arrhythmia Agents