Katsura Sakaki

Time-domain T-wave alternans measured from Holter electrocardiograms predicts cardiac mortality in patients with left ventricular dysfunction: A prospective study

BACKGROUND Time-domain T-wave alternans (TWA) is useful for identifying patients at risk for serious events after myocardial infarction. OBJECTIVE The purpose of this study was to prospectively evaluate the utility of time-domain TWA measured from Holter ECGs in predicting cardiac mortality in patients with left ventricular (LV) dysfunction. METHODS Two hundred ninety-five consecutive patients with LV dysfunction were enrolled in the study. Patients were divided into two groups: the ischemic group (n = 195) and the nonischemic group (n = 100). Time-domain TWA was assessed using the modified moving average method from routine 24-hour Holter ECGs recorded during daily activity. The maximal time-domain TWA voltage at heart rate <or=120 bpm in either lead V(5) or V(1) was derived and its value defined as positive when the voltage was >or=65 microV. The primary end-point was defined as cardiac mortality. RESULTS Mean maximal time-domain TWA voltage was 54 +/- 16 microV. During follow-up of 390 +/- 212 days, 27 patients (17 in the ischemic group and 10 in the nonischemic group) died of cardiac causes. Fifty-three patients (18%) were time-domain TWA positive and 242 (82%) were time-domain TWA negative. Univariate Cox proportional hazards analyses revealed that older age, New York Heart Association functional class III or IV, diabetes, renal dysfunction, nonsustained ventricular tachycardia, and time-domain TWA were associated with cardiac mortality. In multivariate analysis, time-domain TWA had the most significant value (hazard ratio = 17.1, P <.0001). This index also was significant in both subgroups (ischemic group: hazard ratio = 19.0, P <.0001; nonischemic group: hazard ratio = 12.3, P = .002). CONCLUSION Time-domain TWA measured from 24-hour Holter ECGs predicts cardiac mortality in patients with ischemic and nonischemic LV dysfunction.

Quantitative assessment of cibenzoline administration for vagally mediated paroxysmal atrial fibrillation using frequency-domain heart rate variability analysis

BACKGROUND Cibenzoline (CBZ), a class I antiarrhythmic drug, has been widely used to maintain sinus rhythm in patients with paroxysmal atrial fibrillation (P-AF). This agent has an anticholinergic action and will become the drug of first choice for vagally mediated P-AF. We assessed its efficacy quantitatively by analyzing the frequency-domain heart rate variability (FD-HRV) of the Holter electrocardiogram (ECG) in patients with vagal P-AF. METHODS We enrolled 65 consecutive patients with vagal P-AF, but 31 patients were excluded because of the occurrence of significant arrhythmias during the 24-h Holter recordings. Accordingly, CBZ was administered to the remaining 34 patients. After administration, a Holter ECG recording was made again. High frequency (HF) components, i.e., vagal tone index, on the FD-HRV analysis from 00:00 h to 06:00 h were used for assessment. In 14 patients, the treatment was changed to disopyramide (DSP) and the same analyses were performed. RESULTS In two patients, the FD-HRV analysis was not utilized after administration. Finally, 32 patients were available for evaluation. CBZ was considered effective for vagal P-AF in 24 patients (75%). After administration, the HF component levels decreased (1589+/-795 ms(2) vs. 850+/-524 ms(2), p<0.0001). Comparison of the pre-administration HF component levels between the CBZ-responsive group and the CBZ-non-responsive group showed higher levels in the CBZ-responsive group (1766+/-758 ms(2) vs. 1058+/-690 ms(2), p=0.026). Although no significant difference in the reduction of the HF component levels was found between CBZ and DSP, DSP had anticholinergic side effects in two patients (14%). CONCLUSIONS In vagal P-AF patients, larger HF components on the FD-HRV analysis could be a hallmark of the antiarrhythmic action of CBZ. The reduction in the HF component levels after drug administration is useful for a quantitative assessment of anticholinergic action.