Circadian variation of the onset of acute myocardial infarction has been noted in many studies and may carry important pathophysiologic implications. However, only a few previous studies have attempted subgroup analyses. In 4,796 patients with documented acute myocardial infarction, the time of symptom onset was recorded. As in other studies, the peak of onset occurred in the morning from 6:01 AM to 12:00 noon, and 28% of the population (1.16 times the average percentage for the other time periods) experienced symptom onset in that period (p<0.001). There was a second, lower peak (25%) in the evening between 6:01 PM and 12:00 midnight, which was also observed in some previous studies. We sought to determine whether or not the presence of subgroups with specific clinical characteristics would exhibit different patterns and thereby contribute to these peaks in the overall population. In patients with a history of congestive heart failure (n=606) or with non-Q wave infarction (n=832), a pronounced peak (29%o) occurred only in the evening. Two nearly equal peaks were observed in patients older than 70 years of age (n = 1,422), smokers (n=2,057), diabetics (n =767), women (n = 1,213), and patients taking ,B-blocking drugs (n = 847). Finally, in patients with a previous myocardial infarction (n = 1,104), no peaks were observed. In a subgroup of patients (n = 1,084) free of the most important modifying factors, there was a single very pronounced late morning peak (32%, 1.39 times the average percentage for the other time periods, p<0.001) without evidence of a second evening peak. It is concluded that marked differences in diurnal patterns of myocardial infarction onset occur in subgroups of patients with modifying factors, particularly non-Q wave infarction, smoking, ,B-blocker use, diabetes, prior congestive heart failure, and prior myocardial infarction. The circadian pattern observed in a given total population reflects the contributions of these subgroups. (Circulation 1989;80:267-275) A circadian variation in the frequency of onset of acute myocardial infarction has been described in a number of studies during the past 25 years.1-8 Most show an increased onset in the morning with a peak incidence between 6:00 AM and 12:00 noon, although a secondary peak in the late evening has also been reported in some studies.1-3,5-7 A circadian variation in onset of other *All editorial decisions for this article, including selection of reviewers and the final decision, were made by a guest editor. This procedure applies to all manuscripts with authors from the
The impact of right bundle branch block on long-term prognosis after anterior wall myocardial infarction is unclear. In 932 patients with Q wave anterior infarction, the short- and long-term prognostic significance of the presence of right bundle branch block was analyzed. Compared with 754 patients without block, 178 patients with right bundle branch block after myocardial infarction showed an increased incidence of left ventricular failure (72% versus 52%, p less than 0.001) and increased in-hospital (32% versus 8%, p less than 0.001) and 1 year after hospital discharge (17% versus 7%, p less than 0.001) cardiac mortality rates. The presence of right bundle branch block was an independent predictor of increased in-hospital and 1-year mortality when entered in a multivariate analysis. However, the absence of left ventricular failure identified a subgroup of patients with right bundle branch block with low in-hospital (4%) and 1 year postdischarge (5%) cardiac mortality rates comparable with those of patients with neither failure nor right bundle branch block (1.7% and 4.8%, respectively). In the presence of left ventricular failure, patients with associated right bundle branch block had higher in-hospital (43% versus 14%, p less than 0.01) and 1 year postdischarge (24% versus 9%, p less than 0.01) cardiac mortality rates than those of patients with failure but no right bundle branch block. Thus, the presence of right bundle branch block after anterior myocardial infarction is an independent marker of poor prognosis.(ABSTRACT TRUNCATED AT 250 WORDS)
To study the effect of coronary angioplasty (PTCA) on left ventricular (LV) diastolic filling, mitral Doppler flow tracings of 15 patients with isolated stenosis of the left anterior descending coronary artery (LAD) and normal systolic LV function were recorded before PTCA as well as 24 h and 3 months after successful PTCA. Compared to control subjects, patients with LAD stenosis exhibited an abnormal LV filling velocity pattern before PTCA. The day following PTCA, the ratios of the early peak diastolic velocity to the peak late diastolic velocity and of the time velocity integral of the early diastolic filling phase to the time velocity integral of the late diastolic filling phase were unchanged. Despite the absence of clinical evidence of restenosis, LV filling remained abnormal 3 months after PTCA. The results suggest that abnormalities of the LV filling velocity in patients with isolated LAD stenosis and normal systolic function may persist as long as 3 months after PTCA.
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