Effect of nifekalant on life-threatening ventricular arrhythmias in patients with cardiopulmonary resuscitation or during the perioperative state

Background: Nifekalant is a unique class III anti-arrhythmic agent with a strong effect on prolonging the myocardial refractoriness, but its clinical effect is still unclear. In this study, we evaluated the effect of nifekalant on life-threatening ventricular arrhythmias and compared the clinical background between the effective and non-effective patients in order to clarify the clinical factors which may have an influence on the efficacy of nifekalant. Methods: The study population consisted of 47 consecutive patients who underwent nifekalant administration for life-threatening ventricular arrhythmias (VT/VF). Their clinical characteristics and ECG parameters were retrospectively compared between patients with and without an effective result with the nifekalant administration. Results: Nifekalant was effective for refractory VT/VF in 26/47 patients. There was no significant difference in the age, gender or left ventricular ejection fraction, but the incidence of ischemic heart disease was higher in the effective group (17/26) than non-effective group (9/21, p = 0.004). The incidence of in-hospital events was higher in the effective group than non-effective group (20/26 vs 10/21, p = 0.037). A significant prolongation in the QTc interval was observed in all patients and the degree of QTc prolongation was greater in the effective group than in the non-effective group (0.46 ± 0.04 vs 0.43 ± 0.02 sec1/2, p = 0.026). Conclusion: Nifekalant was effective in 55% of the patients for refractory VT/VF. It was considered that nifekalant was more effective for patients with ischemic heart disease, during the perioperative period or in those experiencing in-hospital events. The prolongation of the QTc interval might also be useful as an index for the efficacy of nifekelant administration.