No cardiac testing for intermediate-risk patients on β-blockers was noninferior to testing before vascular surgery for preventing death and nonfatal MIPDF
ACP J Club. 2007 Jan-Feb;146:20. doi:10.7326/ACPJC-2007-146-1-020
Clinical Impact Ratings
Poldermans D, Bax JJ, Schouten O, et al. Should major vascular surgery be delayed because of preoperative cardiac testing in intermediate-risk patients receiving beta-blocker therapy with tight heart rate control? J Am Coll Cardiol. 2006;48:964-9. [PubMed ID: 16949487]
In intermediate-risk patients receiving β-blocker therapy for tight control of heart rate, is a strategy of no cardiac testing noninferior to a strategy of testing before major vascular surgery for preventing cardiac death and nonfatal myocardial infarction (MI)?
Design: Randomized controlled noninferiority trial.
Blinding: Blinded (outcome assessors).*
Follow-up period: Median 2 years.
Setting: 5 clinical centers in Europe and Brazil.
Patients: 770 patients (mean age 68 y, 75% men) scheduled for elective open abdominal aortic or infrainguinal arterial reconstruction who had intermediate cardiac risk defined as 1 or 2 of the following: age > 70 y, angina pectoris, previous MI, history of congestive heart failure, drug therapy for diabetes mellitus, serum creatinine > 160 µmol/L, and previous stroke or transient ischemic attack.
Intervention: No preoperative cardiac testing (n = 384) or dobutamine echocardiography or dipyridamole perfusion scintigraphy testing (n = 386). Patients with extensive ischemia were considered for revascularization before surgery. Patients in both groups who were already taking β-blockers continued using them; others started with bisoprolol 2.5 mg daily. The β-blocker dose was carefully adjusted to maintain a resting heart rate of 60 to 65 beats/min without bradycardia or hypotension before and after surgery.
Outcomes: Composite endpoint of cardiac death or nonfatal MI at 30 days after surgery. Secondary outcome was the composite endpoint at 2 years.
Patient follow-up: 100% at 30 days (intention-to-treat analysis).
In the testing group, 12 of 34 patients with extensive ischemia had revascularization (10 percutaneous coronary interventions, 2 bypass surgeries) and 6 were successful. The strategy of no cardiac testing was noninferior to testing for preventing a composite endpoint of cardiac death or nonfatal MI at 30 days (Table). The groups did not differ for the composite endpoint at 2 years (3.1% for the no-testing group vs 4.3% for the testing group, P = 0.3). The median duration of screening to vascular surgery was 34 days (range 7 to 88 d) in the no-testing group compared with 53 days (range 13 to 121 d) in the testing group (P < 0.001).
In intermediate-risk patients receiving β-blocker therapy for tight control of heart rate, a strategy of no cardiac testing was not inferior to a strategy of testing before major vascular surgery for preventing cardiac death and nonfatal myocardial infarction.
†Information provided by author.
Source of funding: No external funding.
For correspondence: Dr. D. Poldermans, Erasmus Medical Center, Rotterdam, The Netherlands. E-mail firstname.lastname@example.org.
Table. No cardiac testing vs cardiac testing before major vascular surgery in intermediate-risk patients receiving β-blocker therapy at 30 days after surgery‡
|Outcome||No cardiac testing||Cardiac testing||Difference (1-sided upper 95% CI)|
|Composite endpoint§||1.8% (7/384)||2.3% (9/386)||0.5% (1.2)‖|
‡CI defined in Glossary; difference and CI calculated from odds ratio in article.
§Cardiac death (0.5% vs 1.6%) or nonfatal myocardial infarction (1.3% vs 0.8%).
‖Criteria for noninferiority were met because the difference was < prespecified value of 4%.
Cardiac death and nonfatal MI are common and serious events in the perioperative period, with rates up to 30% in high-risk patients (those with ≥ 3 risk factors based on the Revised Cardiac Risk Index [RCRI]) having vascular surgery (1). Observational studies (2) and some randomized trials (3) suggest that perioperative β-blocker therapy provides myocardial protection in intermediate-risk (RCRI score 1 to 2) and high-risk (RCRI score ≥ 3) patients.
As preoperative coronary revascularization has not been shown to be effective prophylaxis (4), and if it has already been decided that, in the absence of contraindications, β-blocker therapy should be given aiming for tight heart rate control, is there any added value in subjecting intermediate-risk patients to further preoperative cardiac testing? The results of the randomized noninferiority trial by Poldermans and colleagues suggest not. In patients allocated to stress testing and coronary revascularization when appropriate (extensive inducible ischemia and nonurgent surgery), the number of cardiac events at 30 days did not differ from the number not tested. Only 34 of 386 patients (8.8%) who received testing showed extensive ischemia, of whom 14.7% had a cardiac event, and coronary revascularization, achieved in 6 of 12 eligible patients, did not improve the overall outcome of the group. The upper limit of the 95% CI in favor of testing was 1.2% compared with a prespecified noninferiority boundary of 4%, which may seem liberal given an incidence of the primary endpoint of 5% in intermediate risk patients noted in an earlier study (5). However, the observed rates of events in the study by Poldermans and colleagues were much lower than this, and one could also argue that the trial was underpowered to show a significant difference in outcomes owing to test-instigated coronary revascularization.
Ian Scott, MBBS, FRACP, MHA
Princess Alexandra Hospital
Brisbane, Queensland, Australia
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