BACKGROUND: The purpose of this community-wide study was to describe a >2-decade-long experience (1975-97) in the incidence and death rates associated with complete heart block (CHB) in patients with acute myocardial infarction (AMI). Limited population-based data exist describing recent, and changes with time therein, incidence and case-fatality rates associated with CHB complicating AMI.
METHODS: We conducted an observational study of 9082 metropolitan Worcester, Mass, residents (1990 census = 437,000) hospitalized with validated AMI in all greater Worcester hospitals during 11 1-year periods between 1975 and 1997.
RESULTS: Overall, CHB developed in 5.0% of patients with AMI. The incidence rates of CHB declined in the periods studied (6.0% in 1975/78 vs 3.1% in 1997). Declines in the occurrence of CHB were noted in patients with anterior or inferior/posterior MI. These trends remained after adjustment for other factors that might affect the risk of CHB. Patients in whom CHB developed experienced significantly higher hospital death rates than patients in whom CHB did not develop (46.8% vs 14.6%). However, improving trends in the hospital survival rate of patients with CHB were observed between 1975/78 (47.4% surviving) and 1997 (61.3% surviving). Patients in whom CHB developed during hospitalization were not at increased risk for dying after hospital discharge.
CONCLUSIONS: Our findings indicate that the incidence of CHB complicating AMI has declined with time. The hospital prognosis of patients in whom CHB developed has improved, but these patients remain at an increased risk of hospital mortality. The long-term prognosis of patients with inferior MI and CHB is similar to that of patients in whom CHB did not develop. Patients with anterior MI and CHB may be at an increased risk of long-term mortality.
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