Prognostic significance of ST segment changes in lead aVR in patients with acute inferior myocardial infarction with ST segment elevation.

BACKGROUND

Patients with inferior wall ST segment elevation myocardial infarction (STEMI) are considered to be at lower risk than patients with anterior wall STEMI. Nonetheless, 30-40% of all acute inferior wall MI cases have a poor prognosis.

AIM

To assess the frequency of ST segment changes (elevation or depression) in lead aVR in inferior STEMI patients, and to determine the clinical course and short-term prognosis of such patients.

METHODS

The study retrospectively analysed the records of 320 consecutive patients with inferior wall STEMI (206 males, 114 females, mean age 65.6 ± 11.1 years). Patients were divided into three groups based on treatment: group A, primary percutaneous coronary intervention (134 patients); group B, fibrinolytic therapy (96 patients); and group C, conservative treatment (no reperfusion therapy) (90 patients). The mean time from onset of pain to the first ECG for all patients was 6.1 h. The total number of in-hospital deaths was 29 (9.0%), comprising 11 (8.2%) in group A, seven (7.3%) in group B, and 11 (12.2%) in group C (NS). The mean maximum creatine phosphokinase was 2,021 ± 1,837 U/L in group A, 1,734 ± 1,581 U/L in group B, and 1,217 ± 981 U/L in group C (p = 0.01). The mean left ventricular ejection fraction was 50.2% ± 9.0%, 54.9 ± 8.6%, and 51.3% ± 9.7% for groups A, B and C, respectively (NS).

RESULTS

ST segment changes in lead aVR were observed in 135 (42.2%) patients, comprising elevation in 47 (14.7%) patients and depression in 88 (27.5%) patients. The in-hospital mortality rates for patients with ST segment elevation, ST segment depression, and no ST segment changes were 27.7%, 16.5%, and 1.0%, respectively (p 〈 0.001). For group A, the in-hospital mortality rate was higher in patients with ST segment elevation than in patients with no ST segment changes (15.4% vs 1.2%, p 〈 0.001). For group B, the in-hospital mortality rates were 33.3%, 12.9%, and 0%, in patients with ST segment elevation, ST segment depression, and no ST changes, respectively (p = 0.006). For group C, the in-hospital mortality rate was higher in patients with ST segment elevation (32%) than in patients with ST segment depression (12.5%) and patients with no ST segment changes (2%, p = 0.006). Logistic regression analysis found that female gender, diabetes, hypertension, lower ejection fraction, and cardiogenic shock on admission were independent predictors of ST segment elevation.

CONCLUSIONS

ST segment changes in lead aVR occurred in approximately half of inferior wall STEMI patients. The presence of such ST segment changes was associated with a poorer prognosis during the hospital stay, and the changes were not associated with the type of reperfusion treatment.