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

Abstract

Background: Although second- and third-degree heart block (HB) are 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-HB 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.