[Study of lethal arrhythmias using Holter ECG monitoring].

Holter monitorings were performed on 2733 cases (male 1547, female 1186; age 16-92 yrs.) from 1973 to 1986 in our hospital. Among these cases, 18 patients (0.66%) died suddenly (group A), 47 patients (1.72%) died of cardiac failure (group B) and 142 patients (5.27%) survived irrespective of the presence of advanced arrhythmias (group C). To evaluate the precipitating factors for sudden cardiac death (SD), underlying diseases, electrical instability and clinical characteristics were compared between each group. 1. The incidence of coronary artery disease (CAD) was 6 cases (33.3%) in group A, 13 cases (27.8%) in group B and 70 cases (49.3%) in group C. There were no significant differences in the incidence of CAD between each group. 2. The incidence of ventricular tachycardia (VT) was 5 cases (27.8%) in group A, 13 cases (27.7%) in group B and 33 cases (23.2%) in group C. Paroxysmal atrial fibrillation (PAf) also showed the higher incidence in group A. 3. The subjects older than 60 years old were 4 cases (22.2%) in group A, 30 cases (63.8%) in group B and 60 cases (42.2%) in group C. The sex ratios were higher in male (over 60%) in 3 groups than in female. 4. In patients with CAD, VT showed higher incidence in SD (3/6 cases (50.0%)), cardiac death (CD) (6/13 cases (46.2%)) and those who survived with myocardial infarction (11/30 cases (36.7%)). 5. In patients with CAD, the reproducibility of advanced arrhythmias was found in 1/3 cases (33.3%) for SD and in 6/9 cases (66.7%) for CD. 6. Heart rate variability evaluated by RR50 (total number of changes in successive RR intervals greater than absolute value of 50 msec.) showed smaller value in the night (3:00 a.m.) than in the daytime (3:00 p.m.) in the patients with SD and CD. The night value of RR50 was significantly lower in patients with SD than in patients with CAD (p less than 0.05). The above results suggest that the presence of coronary artery disease, VT, PAf, decrease in RR50 at night and sex (male) will be precipitating factors for sudden cardiac death.