Are chest pain imaging guidelines triggering overdiagnosis?

Current guidelines that call for routine noninvasive testing of low-risk chest pain patients may be based on outdated evidence and should be scrutinized via randomized trial, according to an article in the Oct. 22 issue of Archives of Internal Medicine.

The American College of Cardiology (ACC)/American Heart Association (AHA) guidelines aim to reduce the risk of a missed myocardial infarction (MI) by recommending stress testing or coronary CT angiography (CCTA) for patients with resolved chest pain and no electrographic or biomarker abnormalities. However, the approach may miss the mark and ignite a diagnostic and interventional cascade that does not improve patient outcomes.

Critical questions remain unanswered, according to Vinay Prasad, MD, and Michael E. Cheung, MD, both of Northwestern University in Chicago, and Adam Cifu, MD, of University of Chicago. These include:

• Does current practice lead to stenting of asymptomatic patients in cases where the pain was noncardiac?
• Does practice improve outcomes?

The authors referred to a list of evidence to suggest the guidelines need to be re-examined.

Proponents of noninvasive testing often cite data indicating that 2 percent of patients with MI are inappropriately discharged from the ED. However, the authors noted this statistic is based on 1993 data, which pre-dated routine use of cardiac serum biomarker testing. Current practice uses biomarkers and more sensitive assays, and may have put a dent in the missed-MI rate.

Prasad and colleagues acknowledged that stress testing and CCTA can identify patients at higher risk for adverse outcomes, but they questioned whether interventions based on these findings lead to improved outcomes. They emphasized several points:

• Previous studies have not demonstrated a benefit to revascularization of these patients;
• Noninvasive imaging may lead to revascularization of asymptomatic lesions;
• Medical management should be the initial approach for most patients with angina and significant coronary lesions; and
• Revascularization is not a reliable end point. It does not automatically decrease future events or mortality.

The authors continued: “Despite a significant investment of financial resources in our current system, there is direct evidence that we are not reducing the rate of cardiovascular events.” They referred to the nearly three-fold increase in imaging stress tests, doubling of primary coronary angiography and seven-fold increase in the use of coronary stents among Medicare beneficiaries from 1993 to 2001. At the same time, the rate of hospitalization for acute MI held steady.

“Thus, our current practice may simply be increasing the diagnosis of CAD [coronary artery disease], without preventing negative outcomes, a problem increasingly recognized as overdiagnosis in medicine.”

Prasad and colleagues called for a randomized trial comparing noninvasive testing to a strategy of no further intervention. The findings, they noted, could change management of resolved chest pain by omitting stress testing or CCTA.