Prognostic significance of isolated sinus tachycardia during first three days of acute myocardial infarction.

Sinus tachycardia often accompanies other indicators of poor prognosis in acute myocardial infarction. This study was performed to evaluate the prognostic significance of early (Days 1 to 3) in-hospital sinus tachycardia (isolated sinus tachycardia) in the absence of other common indicators of poor prognosis. All patients consecutively admitted directly to the cardiac care unit during a six-year period were evaluated. Patients who had confirmed acute myocardial infarction and no urgent complications during Days 1 to 3 with isolated sinus tachycardia (99 patients) or without isolated sinus tachycardia (159 patients) were included in the study. Both groups were followed for subsequent in-hospital outcome and long-term survival. Univariable and multivariable analysis of historical and demographic characteristics showed no significant differences between the two groups. When clinical descriptors of the infarct were evaluated, the group with isolated sinus tachycardia had a significantly higher mean peak creatine kinase level (p = 0.0007), a larger proportion of anterior infarcts and multiple infarct sites (p less than 0.001) by electrocardiography, a higher incidence of peri-infarction pericarditis (p = 0.007), and a higher incidence of recurrent chest pain (p = 0.03). Twenty-five patients (25 percent) in the group with isolated sinus tachycardia had subsequent urgent complications during the hospitalization compared with 11 patients (7 percent) in the control group (p = 0.00005). In multivariable analysis, isolated sinus tachycardia was an independent predictor of subsequent urgent complications (p = 0.0009) and mortality (p = 0.05).