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

Background Although second- and third-degree heart block (HB) ore common co nduction disorders associated with acute myocardial infarction (MI), patien t 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 developmen t of HB. HB and non-MB patients were compared by univariate analysis, and t he influence of HB on outcomes was evaluated by unadjusted and multiple log istic regression. Results HB was documented in 5048 (4.7%) patients; 1646 presented with HB a nd 3402 developed HB during hospitalization. HB was more common among patie nts with inferior infarctions than anterior infarctions (7.3% vs 3.0%, P = .001), particularly the cohort of patients with inferior MI treated with re perfusion therapy (8.3%). HB patients had higher rates of in-hospital morta lity (29.6% vs 17.5% vs non-HB patients, P = .001). After adjustment for de mographic 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 s urvivors (RR 0.94, 95% CI 0.88-1.01). Mortality risks varied on the basis o f 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-hos pital mortality. There was a trend toward increased mortality among patient s with anterior MI (RR 1.15, 95% CI 0.99-1.32) at 1 year, whereas those wit h 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, pa rticularly among patients with inferior Mis who received reperfusion therap y. HB is independently associated with short-term but not long-term mortali ty.