Are reciprocal changes a consequence of "ischemia at a distance" or merely a benign electrical phenomenon? A pulsed-wave tissue Doppler echocardiographic study

Abstract

Objectives: The aim of the present study was to investigate whether ST segment depression in precordial leads at the time of acute inferior myocardial infarction represents a reciprocal change rather than concurrent anterior wall ischemia on the surface electrocardiography.

Background: The mechanism of reciprocal ST segment depression during acute myocardial infarction is controversial. "Ischemia at a distance" or a benign electrical phenomenon has been implicated in numerous reports. Pulsed-wave tissue Doppler (PWTD) echocardiography can be used to examine the regional diastolic motion of the left ventricular myocardial wall and may allow the detection of ischemic segments.

Methods: We evaluated regional myocardial ischemia using PWTD echocardiography in 48 patients with a first inferior wall myocardial infarction. The left ventricle was divided into 16 segments. PWTD echocardiographic velocities were obtained from each left ventricular segments.

Results: Reciprocal ST segment depression was present in 35 patients (Group 1) but not in the remaining 13 patients (Group 2). There were no significant differences between groups 1 and 2 with respect to systolic (S) (7.4 +/- 1.1 vs 6.8 +/- 0.9 cm/s; P > 0.05), early (E) (10.5 +/- 2 vs 9.4 +/- 1.2 cm/s; P > 0.05), and late (A) (9.5 +/- 3.2 vs 8.5 +/- 2.3 cm/s; P > 0.05) diastolic waves peak velocities, E/A ratio 1.1 +/- 0.2 vs 1.1 +/- 0.1; P > 0.05), Ewave deceleration time (DT) (92 +/- 17 vs 101 +/- 16 ms; P > 0.05) and regional relaxation time (RT) (82 +/- 19 vs 93 +/- 21 ms; P > 0.05) in anterior wall (basal levels), which correspond to reciprocal ST segment depression on electrocardiography. According to E/A ratio detected by PWTD echocardiography in anterior wall and anterior septum, patients with reciprocal ST segment depression were also divided into two groups: Group A, with E/A ratio > 1; Group B, with E/A ratio < 1. Among the 35 patients with reciprocal ST segment depression, anterior wall ischemia was present in 10 patients and absent in 25 patients, whereas anterior septal ischemia was present 12 patients and absent in 23 patients.

Conclusions: Reciprocal ST segment depression during the early phases of inferior infarction is an electrical reflection of primary ST segment elevation in the area of infarction.