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Clinical Significance and Contributing Factors of Long‐Term Variability in Induced Ventricular Tachyarrhythmias
Author(s) -
HAYASHI MEISO,
KOBAYASHI YOSHINORI,
MORITA NORISHIGE,
IWASAKI YUKI,
OHMURA KAZUKO,
ATARASHI HIROTSUGU,
KATOH TAKAO,
TAKANO TERUO
Publication year - 2003
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1046/j.1540-8167.2003.03164.x
Subject(s) - medicine , amiodarone , cardiology , thallium , ejection fraction , implantable cardioverter defibrillator , ventricular tachycardia , clinical significance , logistic regression , ventricular fibrillation , heart failure , atrial fibrillation , inorganic chemistry , chemistry
Ventricular arrhythmias induced during electrophysiologic study (EPS) may vary over time, making arrhythmia induction studies unreliable. The aim of this prospective study was to clarify the clinical significance of long‐term variability in induced arrhythmias and to elucidate factors determining this variability. Methods and Results: Three noninvasive EPSs were performed 1, 13, and 25 months after implantation of a cardioverter defibrillator in 40 patients with ventricular tachyarrhythmias, without a change in their antiarrhythmic drug regimens. The induced ventricular arrhythmias were categorized into five grades. Long‐term variability, which was defined as a variation in the grades during the three EPSs, was observed in 23 patients (group A) and not in the remaining 17 patients (group B). During the 2‐year period, spontaneous sustained ventricular arrhythmias developed in 15 patients (65%) in group A but in only 4 patients (24%) in group B (P = 0.01). Inducibility of sustained tachyarrhythmias was not associated with emergence of spontaneous arrhythmias. All patients also underwent thallium‐201 and iodine‐123‐metaiodobenzylguanidine (MIBG) scans to evaluate the extent of the regions showing normal thallium uptake with reduced MIBG uptake. Group A patients showed greater thallium/MIBG mismatched regions than did group B patients (P = 0.01). Logistic regression analysis revealed that long‐term variability (relative risk [RR] 7.55, P = 0.03), amiodarone therapy (RR 0.14, P = 0.04), and left ventricular ejection fraction <35% (RR 6.26, P = 0.04) were independent predictors of spontaneous arrhythmia occurrence. Conclusion: In patients with ventricular tachyarrhythmias, long‐term variability in induced arrhythmias, but not the inducibility of arrhythmias, is associated with a higher incidence of spontaneous arrhythmias. Regional cardiac sympathetic denervation may be an important mechanism of this variability. These results also may explain why inducibility‐based antiarrhythmic drug testing does not predict patient prognosis. (J Cardiovasc Electrophysiol, Vol. 14, pp. ***‐***, October 2003)