Intraventricular conduction disturbances in acute myocardial infarction: short- and long-term prognosis.

Short- and long-term prognosis were analysed in 59 patients admitted in the coronary care unit with an acute myocardial infarction, complicated with acute intraventricular (IV) conduction defects. In-hospital mortality of patients with IV conduction disturbances was more than twice (30%) the mortality of patients without IV conduction defects (13%; P less than 0.001). Mortality rate was very high among patients with all forms of incomplete trifascicular block or complete right bundle-branch block. Among survivors of the group with conduction defects, late death rate was significantly higher than in survivors of the group without IV blocks (25 vs 8%; P less than 0.01). Short-term prognosis of conduction defects in myocardial infarction depends on the extent of the necrosis. The conflicting results in long-term prognosis could be ascribed to variations in patient material and to different criteria used to define the acute nature of a block. Lastly the variable prognosis could correspond to differences in the site of the lesions within the conduction pathway.