Search

Objective To document the frequency of conduction defects and their influence on prognosis in a large series of patients with acute myocardial infarction who underwent coronary care during a period when thrombolytic therapy was in common usage.Background Conduction defects have been associated with an adverse prognosis following acute myocardial infarction, but there are few data on the incidence and outcome of conduction defects since the introduction of thrombolytic therapy.Patients and methods The study group comprised 1225 consecutive patients with acute myocardial infarction treated in the coronary care unit from I January 1988 to 31 December 1994. Conduction defects were recorded prospectively and were classified as follows: complete atrioventricular node block associated with narrow complex escape rhythms; left or right bundle branch block; bifascicular block; complete heart block involving both bundle branches.Results Electrocardiographic data were available in 1220 patients. Complete atrioventricular node block occurred in 65 (5.3%), left and right bundle branch block in 29 (2,4%) and 44 (3.6%), bifascicular block in 36 (2.9%) and complete heart block involving both bundle branches in 20 (1.6%). The more advanced degrees of block in the bundle branches occurred more commonly in patients with diabetes, previous infarction, Q-wave infarction, anterior infarction and left ventricular failure. Survival analysis showed an increased short- and long-term cardiac mortality in patients with conduction defects, prognosis worsening as the severity of the conduction defect increased.Conclusion Conduction defects complicated acute myocardial infarction in 16% of cases and had a graded impact on the short- and long-term prognosis, patients with advanced bundle branch involvement faring worst. The data showed a small decline in the rate of severe conduction defects compared with previous studies, possibly reflecting the beneficial effects of thrombolytic therapy on infarct size. [ABSTRACT FROM PUBLISHER]

OBJECTIVE--To compare the circadian rhythm of myocardial ischaemia in patients with stable angina with that in patients in the early postinfarction period with particular emphasis on the role of the autonomic nervous system. PATIENTS--44 patients with stable angina and ischaemia on treadmill testing (group A) were compared with 131 patients in the early postinfarction period (group B). All had 48 hour ambulatory Holter monitoring. SETTING--Coronary care unit and cardiology department of a district general hospital. DESIGN--Prospective, between group, comparative study. RESULTS--337 ischaemic episodes occurred in 35 patients in group A and 370 ischaemic episodes occurred in 65 patients in group B. 34% of patients in group A had only silent episodes of ischaemia compared with 97% in group B (p < 0.0001). In group A ischaemic episodes showed a circadian rhythm that peaked during the daytime hours (p < 0.0001), but this was not seen in group B. Both the high (0.15-0.40 Hz) and low (0.04-0.15 Hz) frequency spectral components of heart rate variability showed a clear circadian rhythm (p < 0.0001); peak values occurred during the sleeping hours, although this pattern was less pronounced in group B. The ratio of low to high frequency variability (a measure of sympathovagal balance) showed a peak in daytime hours in group A (p < 0.002), but this was not seen in group B. CONCLUSION--In stable angina, myocardial ischaemia peaks during the day and is associated with a similar circadian rhythm of sympathovagal balance. In the early postinfarction period both the ischaemic and sympathovagal rhythms are severely diminished or lost altogether. Circadian changes in sympathovagal tone may explain, at least in part, the circadian rhythm of ambulatory myocardial ischaemia in patients with stable angina. [ABSTRACT FROM PUBLISHER]