Non-Q wave perioperative myocardial infarction: assessment of the incidence and severity of regional dysfunction with quantitative two-dimensional echocardiography
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Hypothermic potassium cardioplegia reduces perioperative mortality, but new research shows it does not prevent all myocardial infarctions. Postoperative myocardial infarctions without Q waves are still common, indicating a need for further investigation.
Area of Science:
- Cardiology
- Cardiac Surgery
Background:
- Hypothermic potassium cardioplegia has reduced mortality and Q wave myocardial infarctions.
- The impact on non-Q wave myocardial infarctions remains unevaluated.
Purpose of the Study:
- To assess the incidence of non-Q wave myocardial infarctions after cardiac surgery.
- To evaluate regional wall motion abnormalities (RWMAs) and global left ventricular function deterioration.
Main Methods:
- Utilized quantitative two-dimensional echocardiography for RWMAs.
- Employed first-pass radionuclide ventriculography for left ventricular function.
- Categorized 65 patients based on postoperative creatine kinase-MB levels and Q wave development.
Main Results:
- Incidence of RWMAs increased with CK-MB levels (0% to 89%).
- Patients with RWMAs showed similar left ventricular function deterioration regardless of Q wave presence.
- Non-Q wave myocardial infarctions are a significant concern.
Conclusions:
- Hypothermic potassium cardioplegia does not eliminate all myocardial infarctions.
- Regional wall motion abnormalities are common post-surgery, even without Q waves.
- Further strategies are needed to prevent non-Q wave myocardial infarctions.
Abstract:
Since the widespread use of hypothermic potassium cardioplegia began, marked reductions in perioperative mortality and the rate of Q wave-associated myocardial infarctions have been noted. No study to date has evaluated whether there has been an equally dramatic improvement in the incidence of postoperative myocardial infarctions unassociated with Q wave development. We used a previously validated quantitative two-dimensional echocardiographic analytic algorithm to determine the incidence and severity of regional wall motion abnormalities (RWMAs) and first-pass radionuclide ventriculography to assess deterioration in global left ventricular function in the four following groups of patients (total n = 65): (1) those with peak postoperative creatine kinase (CK)-MB levels equal to or less than the mean value for patients undergoing coronary artery bypass surgery at our institution (n = 10), (2) those with CK-MB levels between the mean and 1 SD above the mean (n = 10), (3) those with peak CK-MB levels higher than 1 SD above the mean (n = 25), and (4) those with new pathologic Q waves on the postoperative electrocardiogram (n = 20). All patients had electrocardiograms without pathologic Q waves and normal wall motion and ejection fraction by contrast ventriculography before surgery. The incidence of postoperative RWMA by two-dimensional echocardiography for groups 1 through 4 was 0%, 20%, 55%, and 89%, respectively. Percent of abnormal left ventricular segments, wall motion scores, and the deterioration in left ventricular ejection fraction as assessed by radionuclide ventriculography were similar for patients with new RWMAs whether or not new Q waves developed (p = NS for all).(ABSTRACT TRUNCATED AT 250 WORDS)