Surgery shortly after an MI still contraindicated?

An administrative database from the state of California suggests that surgery in the first month after an MI greatly increased the chances of reinfarction, and significantly increased the risk of death.  Vascular patients actually had lower RRs than other NCS, suggesting that the atherosclerotic burden is more uniformly increased in vascular patients compared to others (hips, colon resection), or that clinicians were more careful and/or attuned to caring for the vascular patients.

RESULTS: Postoperative MI rate for the recent MI cohort decreased substantially as the legth of time from MI to operation increased (0-30 days = 32.8%, 31-60 days = 18.7%, 61-90 days = 8.4%, and 91-180 days = 5.9%), as did 30-day mortality (0-30 days = 14.2%, 31-60 days = 11.5%, 61-90 days = 10.5%, and 91-180 days = 9.9%). MI within 30 days of an operation was associated with a higher risk of postoperative MI (RR range = 9.98-44.29 for the 5 procedures), 30-day mortality (RR range, 1.83-3.84), and 1-year mortality (RR range, 1.56-3.14).

CONCLUSIONS: A recent MI remains a significant risk factor for postoperative MI and mortality following surgery. Strategies such as delaying elective operations for at least 8 weeks and medical optimization should be considered

Many things have changed since Rao and El-Etr‘s classic paper:

  • TnI and CKMB are much more sensitive and more likely to be used as a screening tool than simply after symptoms occur.  Therefore, we suspect that the MIs detected in th 21st century may be smaller than in the past, but more prevalent.
  • PCI and more optimal medical Rx are available today, which might reduce the likelihood and lethality of reinfarction

The authors did not address the impact of medical Rx nor revascularization in this study.  However, the same group (least publishable units?) published another paper suggested that preop PCI or CABG protects against reinfarction.   They state:

Patients with a recent MI who were revascularized before surgery had an approximately 50% decreased rate of reinfarction (5.1% versus 10.0%; p < 0.001) and 30-day (5.2% versus 11.3%; p < 0.001) and 1-year mortality (18.3% versus 35.8%; p < 0.001) compared with those who were not. Stenting within 1 month of surgery was associated with a trend toward increased reinfarction (relative risk: 1.36; 95% CI, 0.96-1.97), and coronary artery bypass graft was associated with a decreased risk (relative risk: 0.70; 95% CI, 0.55-0.95).

Again, there are selection biases:

  • Emergent cases are probably too sick to wait for revascularization.
  • Some sick/frail patients may not be felt to be good candidates for revascularization.

In fact, only ~12% of revascularizations occurred in the 3 months before surgery.  At surgery < 1 month after original MI, reinfarction rates were high (~1/3) and no lower in the revascularization group.

For patients undergoing vascular surgery, early revascularization (within 1 month of MI) was associated with lower reinfarction rates compared with no revascularization (21.3% versus 34.2%; p = 0.026). In contrast, for those undergoing nonvascular surgery, reinfarction rates were greater for revascularized patients (40.4% versus 31.6%; p = 0.038). Patients undergoing vascular surgery were more likely to receive CABG than PTCA (53.7% versus 46.3%), but the reverse was true for nonvascular surgery (41.2% versus 58.8%) (p < 0.001). This pattern of revascularization was also seen for patients undergoing surgery within 1 month of MI (vascular: 43.8% CABG versus 56.3% PTCA; nonvascular: 32.9% CABG versus 67.1% PTCA; p = 0.10).

Lastly, the authors mention that the CARP trial did not show survival benefits for coronary revascularization before vascular surgery, but did suggest lower rates of MI after CABG than PCI, as these authors have also shown.

The debates continue!

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