Correspondence
Preoperative Assessment of Patients with Coronary Disease
N Engl J Med 1996; 334:1064-1065April 18, 1996
- Article
To the Editor:
Drs. Mangano and Goldman (Dec. 28 issue)1 recommend that all patients with known coronary disease undergo routine postoperative electrocardiography on day 1 and again before discharge from the hospital, to rule out myocardial infarction. Used this way, electrocardiography would be considered a screening test (i.e., a means of detecting a common, clinically important disorder in asymptomatic persons).
Unfortunately, neither the clinical circumstances nor the test meets the criteria for a good screening opportunity. Although it is true that a high proportion of patients with perioperative myocardial infarction do not have typical chest pain, the frequency of completely asymptomatic perioperative infarction is extremely low. In our series,2 of the 213 men known to have coronary artery disease who underwent serial electrocardiography and cardiac-enzyme tests during the first three days after surgery, only 3 (1.4 percent) had infarctions that were completely asymptomatic.
In addition, the electrocardiogram is not a valid screening tool in postoperative patients, since it is insensitive and nonspecific. Pathognomonic Q waves develop in only 60 percent of all documented cases of infarction, regardless of the setting.3 Moreover, at least four studies have documented electrocardiographic changes in 20 percent of patients during the first three days after surgery. In most patients, the changes appear to be of no clinical importance and occur in the absence of enzymatic or other evidence of myocardial ischemia or infarction.4
The available evidence demonstrates that routine postoperative electrocardiography in asymptomatic patients, even those known to have coronary artery disease, is of no benefit. In fact, the 20 percent of patients who have electrocardiographic changes would undergo further unnecessary testing and monitoring if electrocardiography were performed routinely after surgery. The evidence indicates that electrocardiography is helpful only as one of the tools, along with cardiac-enzyme tests, to be used in the evaluation of the patient with symptoms or signs of cardiac dysfunction after surgery.
4 ReferencesCarol M. Ashton, M.D., M.P.H.
Nelda P. Wray, M.D., M.P.H.
Veterans Affairs Medical Center, Houston, TX 77030-42981
Mangano DT ,Goldman L . Preoperative assessment of patients with known or suspected coronary disease. N Engl J Med 1995;333:1750-1756
Full Text | Web of Science | Medline2
Ashton CM ,Petersen NJ ,Wray NP , et al. The incidence of perioperative myocardial infarction in men undergoing noncardiac surgery. Ann Intern Med 1993;118:504-510
Web of Science | Medline3
Horan LG ,Flowers NC ,Johnson JC . Significance of the diagnostic Q wave of myocardial infarction. Circulation 1971;43:428-436
Web of Science | Medline4
Ashton CM ,Thomas J ,Wray NP ,Wu L ,Kiefe CI ,Lahart CJ . The frequency and significance of ECG changes after transurethral prostate resection. J Am Geriatr Soc 1991;39:575-580
Web of Science | Medline
To the Editor:
On the basis of our experience,1 it is important to view patients with peripheral vascular disease and asymptomatic coronary artery disease as a group at high risk for three-vessel coronary artery disease and late cardiac events. We followed 84 patients with peripheral vascular disease but without symptoms of coronary artery disease for a mean of five years after performing base-line coronary angiography, thallium scintigraphy, and radionuclide ventriculography. This asymptomatic cohort, although small, had a high incidence of coronary artery disease (69 percent), with three-vessel disease in 16 percent of the patients. Forty-two patients underwent vascular reconstructive procedures, with no perioperative deaths and only one nonfatal myocardial infarction. However, late cardiac events (defined as myocardial infarction or death from a cardiac cause) occurred in 22 patients (26 percent).
1 ReferencesDawood Darbar, M.B., Ch.B.
Vanderbilt University School of Medicine, Nashville, TN 37232-6603Neil Gillespie, M.B., Ch.B.
Ninewells Hospital and Medical School, Dundee DD1 9SY, ScotlandAuthor/Editor Response
The authors reply:
To the Editor: We agree with Drs. Darbar and Gillespie that patients with peripheral vascular disease and asymptomatic coronary artery disease are at high risk for late cardiac events. As demonstrated by their own data, however, the perioperative risk in such patients is sufficiently low that aggressive preoperative evaluation is not generally needed. As we emphasized in our review, these patients should be reassessed after surgery to be sure that improvement in their peripheral vascular symptoms has not unmasked symptomatic coronary disease. Current data do not, in our opinion, allow conclusive recommendations for the evaluation or treatment of patients whose coronary disease remains asymptomatic after the relief of peripheral vascular problems. For patients who remain asymptomatic but inactive because of peripheral vascular disease, more aggressive postoperative approaches may be helpful.
Drs. Ashton and Wray question our recommendation that patients with coronary artery disease undergo routine electrocardiography on the first postoperative day and again before discharge in order to identify possible asymptomatic myocardial ischemia or infarction. They suggest that because only a small number of myocardial infarctions are completely asymptomatic (1.4 percent in their series) and because Q waves are pathognomonic for infarction in only 60 percent of all documented infarctions, electrocardiographic screening should not be performed. Even if their conservative figures are accurate, about 10,000 of the 1 million patients with coronary disease who undergo noncardiac surgery may have an otherwise undiagnosed perioperative myocardial infarction. If the diagnosis of an asymptomatic infarction leads to even a modest prolongation of life, then one can argue that postoperative electrocardiography may well be cost effective, as compared with other accepted medical strategies. Although we agree that we cannot prove the benefit of the routine postoperative electrocardiogram in this setting, we believe at least as strongly that a test with a 1 percent chance of diagnosing a potentially life-threatening condition cannot be so readily dismissed, especially on the basis of data on just 213 patients at one hospital.
Dennis T. Mangano, Ph.D., M.D
Lee Goldman, M.D.
University of California, San Francisco, CA 94121
