Postoperative myocardial infarction (MI) is a well-documented and potentially fatal complication of vascular surgery. Elevated troponin I levels can suggest a myocardial infarction even without ECG evidence. Medical management of ischemic heart disease is well understood, and involves the use of HMG-CoA reductase inhibitors (i.e., statins), antiplatelet drugs, beta-adrenergic receptor blockers, and angiotensin-converting enzyme (ACE) inhibitors. However, it is not clear that we apply our understanding of managing ischemic heart disease to postoperative patients. Dr. Arnaud Foucrier, Department of Anesthesiology and Critical Care, AP-HP Beaujon Hospital, Clichy, France, and colleagues studied vascular surgery patients who suffered perioperative MI or isolated troponin elevation to determine whether such patients received appropriate medical management, and whether this management influenced outcome. The results of their retrospective analysis are published in this month’s Anesthesia & Analgesia in the article titled “The Long-Term Impact of Early Cardiovascular Therapy Intensification for Postoperative Troponin Elevation after Major Vascular Surgery.”
The authors chose patients who underwent elective infrarenal aortic reconstructive surgery. The patients received standard care, including general anesthesia using IV propofol, sufentanil, and atracurium, treatment of postoperative hypertension > 30% of baseline with nicardipine or clonidine, and treatment of tachycardia > 80 bpm with an IV beta blocker. Subcutaneous low molecular weight heparin was administered up to postoperative day 30.
Cardiac troponin I (cTnI) was measured in all patients on arrival at the postanesthetic care unit and on the first, second, and third postoperative days. If there were clinical abnormalities and/or if cTnI concentration was increased, an ECG was performed. Patients were considered to have a postoperative MI if their cTnI concentration was elevated and it was associated with symptoms of ischemia and/or ECG changes indicative of new ischemia (new ST-T changes or new left bundle branch block) and/or development of pathological Q waves on the ECG, and/or imaging evidence of new loss of viable myocardium or new regional wall motion abnormality. If patients experienced a perioperative MI or troponin elevation, treatment was left to the discretion of the attending physician.
Sixty-six or 10% of 647 total patients suffered a perioperative MI. Of the 66 patients who suffered a perioperative MI, 39 (59%) survived to follow-up without a major adverse cardiac event, a mean of 14 months. An expert panel determined that 43 (65%) of the patients with perioperative MI received additional cardiovascular medication during hospitalization, and of these 43 patients, 38 (88%) patients received optimal treatment. Surprisingly, 77% of patients (51) who suffered a perioperative MI had no modification to their cardiovascular treatment at the end of the follow-up. The likelihood of perioperative MI was greater for patients who had no modification of their cardiovascular treatment compared to those who received evidence-based medical therapy.
This is an interesting paper suggesting that following evidenced-based guidelines for management of acute coronary syndrome in postoperative patients will improve long term cardiac outcome. If these retrospective results are confirmed by a prospective randomized control trial, the will influence the postoperative care of all patients undergoing vascular surgery. As Dr. W. Scott Beattie, Department of Anesthesia and Pain Management, University Health Network, Toronto, Ontario, Canada, and colleagues from the University Medical Center Utrecht, Utrecht, the Netherlands, note in their accompanying editorial titled “Perioperative Troponin Elevation: Always Myocardial Injury, But Not Always Myocardial Infarction,” optimized medical therapy “in patients with myocardial injury as detected by troponin elevation after vascular surgery remains an interesting hypothesis that now deserves to be tested prospectively to appropriately answer the question whether this therapy is beneficial or not…The findings of Foucrier et al. offer hope that patients at risk for future major cardiovascular events can be identified by measuring troponin postoperatively and can be treated by focusing on the optimal cardiovascular disease management of those patients with postoperative elevated troponin.”