Does Chronic ST Segment Elevation following Q Wave Myocardial Infarction Exclude Tissue Viability?

Abstract

Purpose: Electrocardiographic (ECG) ST segment elevation lasting 2 or more weeks following Q wave myocardial infarction has been associated with ‘ventricular aneurysm’ and absence of tissue viability. Regional systolic dysfunction may reflect either viable myocardium or scar. Positron emission-tomographic (PET) imaging can distinguish viable from nonviable tissue. We hypothesized that patients with chronic ST segment elevation after Q wave infarction might demonstrate salvageable myocardium in the infarct region. Methods: The ECGs of 1,229 sequential patients undergoing PET scans for viability assessment were reviewed by an electrocardiographer to identify individuals with chronic anteroseptal Q wave infarctions with persistent ST segment elevation exceeding 1 mV. Patients with QRS duration longer than 0.14 ms or rhythm other than sinus were excluded. Viability was considered present if either a reversible stress-induced perfusion defect (ischemia) or a resting perfusion-metabolism mismatch (hibernation) was identified. Results: Anteroseptal ECG Q wave infarction was identified in 132 subjects (74% male, age 61 ± 12 years). Chronic ST segment elevation was present in 84 subjects (64%) and absent in 48. Baseline clinical characteristics and left ventricular systolic function were similar in both groups. 63% of those with and 56% of those without chronic ST elevation had viable myocardium. No relationship was noted between chronic ST segment elevation and the presence or absence of myocardial viability. Conclusions: Chronic ST segment elevation after anteroseptal Q wave myocardial infarction does not exclude myocardial viability in the ‘infarct zone’. Evaluation of residual tissue viability is indicated to assess the benefit of revascularization in patients with Q wave infarction and chronic ST segment elevation.

Myocardial abnormalities underlying persistent ST-segment elevation after anterior myocardial infarction

“…Other authors have suggested that persistent STE, in the setting of reperfused infarction, may be ascribed to residual ischemia arising from areas of viable myocardium at the boundary of necrotic regions [27]. However, in our study this explanation seems to be unlikely, as patients with STE showed transmural necrosis in about 90% of cases, making the presence of viable myocardium in this setting highly unlikely [15].…”

Value of pathologic Q wave in surface electrocardiography in the prediction of myocardial nonviability: A cardiac magnetic resonance imaging-based study

“…using PET scan, chronic ST elevation after Q wave anterior myocardial infarction did not exclude viability. [13]…”