Acute myocardial infarction complicated by heart block in the elderly: Prevalence and outcomes

Background Although second- and third-degree heart block (HB) ore common conduction disorders associated with acute myocardial infarction (MI), patient characteristics and HBs association with outcomes, particularly among the elderly, remain poorly defined. Methods We evaluated 106,780 Medicare beneficiaries aged 65 years and older treated for acute MI between January 1994 and February 1996 for development of HB. HB and non-MB patients were compared by univariate analysis, and the influence of HB on outcomes was evaluated by unadjusted and multiple logistic regression. Results HB was documented in 5048 (4.7%) patients; 1646 presented with HB and 3402 developed HB during hospitalization. HB was more common among patients with inferior infarctions than anterior infarctions (7.3% vs 3.0%, P = .001), particularly the cohort of patients with inferior MI treated with reperfusion therapy (8.3%). HB patients had higher rates of in-hospital mortality (29.6% vs 17.5% vs non-HB patients, P = .001). After adjustment for demographic and clinical factors, HB remained an independent predictor of in-hospital mortality (relative risk [RR] 1.41, 95% confidence interval [CI] 1.34-1.48), but HB had no prognostic significance at 1 year among hospital survivors (RR 0.94, 95% CI 0.88-1.01). Mortality risks varied on the basis of MI location. Both anterior MI (RR 1.46, 95% CI 1.30-1.63) and inferior MI (RR 1.52, 95% CI 1.39-1.66) patients with HB had increased risks of in-hospital mortality. There was a trend toward increased mortality among patients with anterior MI (RR 1.15, 95% CI 0.99-1.32) at 1 year, whereas those with inferior MI were at lower risk (RR 0.83, 95% CI 0.75-0.98). Conclusions HB is a common complication of acute MI in elderly patients, particularly among patients with inferior Mis who received reperfusion therapy. HB is independently associated with short-term but not long-term mortality.