Eligibility for and benefit of thrombolytic therapy in inferior myocardial infarction: focus on the prognostic importance of right ventricular infarction.

OBJECTIVES

This study was undertaken to determine eligibility for and benefit of thrombolytic therapy in patients with acute inferior myocardial infarction with or without right ventricular involvement.

BACKGROUND

Right ventricular involvement commonly complicates acute inferior myocardial infarction and is considered to have prognostic relevance. We hypothesized that the presence of right ventricular infarction, diagnosed early by ST segment elevation in the right precordial lead (V4R), may be of clinical importance in identifying patients who will benefit most from thrombolytic therapy.

METHODS

We studied 200 consecutive patients with acute inferior myocardial infarction to assess the prognostic impact of right ventricular infarction in those considered eligible or ineligible for reperfusion therapy. Prognostic analyses were based on the in-hospital period and a 1- to 6-year follow-up (mean [+/- SD] 37 +/- 12 months).

RESULTS

ST segment elevation in lead V4R was a reliable marker of right ventricular infarction (sensitivity 88%, specificity 78%, diagnostic efficiency 83%) in 107 patients (54%) with inferior myocardial infarction. Seventy-one eligible patients (36%) received thrombolytic therapy and had a lower mortality (8% [6 of 71]) and complication (31% [22 of 71]) rate than ineligible patients (mortality rate 25% [32 of 129], p < 0.01; complication rate 56% [72 of 129], p < 0.01). However, the overall benefit of thrombolysis was restricted to patients with right ventricular infarction complicating acute inferior myocardial infarction (with vs. without thrombolysis, respectively: mortality rate 10% vs. 42%, p < 0.005; complication rate 34% vs. 54%, p < 0.05). In the absence of right ventricular infarction, no difference was observed in the mortality (7% vs. 6%, p = NS) and major in-hospital complication (27% vs. 29%, p = NS) rates, whether or not the patient underwent thrombolytic therapy. Posthospital course over 37 +/- 12 months was not different in patients with and without right ventricular infarction but was best in all patients considered for reperfusion therapy.

CONCLUSIONS

During acute inferior myocardial infarction, the right precordial electrocardiogram is a simple but promising variable to identify a subgroup of patients with an unfavorable course who will benefit most from thrombolytic therapy.