title: Value of electrophysiologic studies in hypertrophic cardiomyopathy treated with amiodarone.
abstract: The relation of electrophysiologic effects of amiodarone to long-term outcome was studied in 35 patients with hypertrophic cardiomyopathy (HC). Indications for electrophysiologic studies were: cardiac arrest (n = 3), syncope/presyncope (n = 27) and asymptomatic ventricular tachycardia (VT) (n = 5). Twenty-eight patients (80%) had VT, 3 (9%) atrial tachycardia and 3 (9%) paroxysmal atrial fibrillation during 24-hour Holter monitoring. The studies were repeated after a total amiodarone dose of 58 +/- 122 g and during a maintenance median daily dose of 400 mg. Amiodarone abolished paroxysmal atrial arrhythmias in all 6 patients. However, it caused marked atrioventricular nodal conduction abnormality in 3 patients and heart block or marked HV interval prolongation (to greater than or equal to 100 ms) in 4 patients. Sustained VT was induced in 26 patients (74%) at baseline study and in 23 patients (66%) taking amiodarone therapy. With amiodarone, VT was no longer inducible or was more difficult to induce in 11 patients (31%), and the drug abolished VT during Holter monitoring in all patients. However, VT was easier to induce with amiodarone or was induced only with amiodarone in 18 (51%) patients. Amiodarone significantly slowed the rate of induced VT (from 248 +/- 29 to 214 +/- 37 beats/min, p less than 0.001). This was associated with a change in its morphology from polymorphic to monomorphic VT in 7 patients. During a follow up of 18 +/- 14 months (range 2 to 56), amiodarone was discontinued because of adverse effects in 8 patients (23%).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Clinical Electrophysiology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: L
authors.initials: L
authors.lastname: Fananapazir
authors.forename: S E
authors.initials: SE
authors.lastname: Epstein
mesh_terms: D000638:Amiodarone / Q000009:adverse effects* / Q000627:therapeutic use; D001145:Arrhythmias, Cardiac / Q000209:etiology*; D002304:Cardiac Pacing, Artificial; D002312:Cardiomyopathy, Hypertrophic / Q000188:drug therapy* / Q000401:mortality / Q000503:physiopathology; D003645:Death, Sudden / Q000209:etiology; D015716:Electrocardiography, Ambulatory; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013610:Tachycardia / Q000175:diagnosis* / Q000188:drug therapy
chemical_list: D000638:Amiodarone