Study Questions Long-Accepted ED Testing Routine for Chest Pain Patients

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Routine stress testing to detect ischemia in patients who present to the emergency department (ED) with chest pain or dyspnea may not be necessary, suggests a single-center study published online October 1, 2014, ahead of print in Circulation: Cardiovascular Imaging. Additionally, researchers found that early revascularization does not correspond with a survival benefit.

 

Methods
Wael A. Jaber, MD, of the Cleveland Clinic (Cleveland, OH), and colleagues followed 5,354 consecutive patients (58.7% female; mean age 59 years) presenting to the hospital’s ED with chest pain (83.8%) or dyspnea (30.2%) from October 2004 to September 2011. Patients underwent myocardial perfusion imaging (MPI) after at least 2 negative troponin T tests and nondiagnostic ECGs. Baseline TIMI risk score distribution was:
  • TIMI 0 or 1: 58.8%
  • TIMI 2: 19.9%
  • TIMI 3: 14.3%
  • TIMI 4 or 5: 7.0%
 
About one-quarter of patients presented with CAD (23.1%) or diabetes (25.6%). Patients who underwent early revascularization were older and more likely to be male and had higher prevalence of comorbid cardiovascular diagnoses, lower mean EF, and more severe perfusion defects. Among patients with inducible ischemia (≤ 5% ischemic myocardium), early revascularization was associated with male sex, known CAD, hyperlipidemia, increasing TIMI scores, higher EF, and more severe perfusion defects.

 


Abnormal MPI (EF < 45%) was found in 19.7% of patients; the ischemic burden was > 5% in 479 patients (9%) and > 10% in 193 patients (3.6%).

The incidence and degree of ischemic myocardium increased with rising TIMI scores. However, the ability of MPI to detect inducible ischemia was low in low-risk patients—showing an incidence of 4.9% in patients with TIMI scores of 0 or 1 and 9.5% in those with TIMI scores of 2—and only moderate for higher-risk patients—19.6% in patients with TIMI scores ≥ 3. A similar pattern was seen for detecting moderate-to-severe ischemia (≥ 10% ischemic myocardium; P < .001 for TIMI scores ≤ 2 vs ≥ 3).

Within 30 days of MPI, invasive angiography was performed in 9.9% of patients, of whom 47.7% had obstructive CAD. Patients with inducible ischemia had higher rates of angiography (74.4% vs 1.2%) and obstructive CAD (52.1% vs 34.0%) compared with those with a normal MPI.

“Therefore, even in patients with evidence of ischemia, significant angiographic CAD on subsequent coronary angiography was often absent,” Dr. Jaber and colleagues write.

Early Revascularization, Mortality Not Linked

The presence and severity of obstructive CAD rose in line with TIMI scores. Similar trends were observed for patients with left main, 3-vessel, or proximal LAD disease and for patients referred for angiography (P < .001 for all trends).

Within 30 days, 0.1% of patients died. A total of 3.5% underwent coronary revascularization, with 8.6% of revascularized patients having a normal MPI. Mortality at a mean follow-up of 3.4 years was 6.5% overall and 11.2% in the subgroup with early revascularization. Inducible ischemia and early revascularization were not associated with mortality after multivariate adjustment, although increasing EF was linked to poorer survival (HR 0.97; 95% CI 0.97-0.98).

A propensity-matched analysis of 141 patients with early revascularization and inducible ischemia confirmed the lack of a relationship between the need for revascularization and mortality (HR 1.00; 95% CI 0.49-2.07).

Study Findings Said to Induce ‘Hate Mail’

“Based on our observations, most patients who present to the ED with chest pain syndromes, negative cardiac biomarkers, and nondiagnostic ECGs should be managed as outpatients with possible stable CAD and not as patients with possible ACS,” Dr. Jaber and colleagues write.

Moreover, they add, “These findings make it difficult to justify routine provocative testing for all patients presenting to the ED with chest pain.”

In a telephone interview with TCTMD, Dr. Jaber said that he has already received “a lot of hate mail” regarding the study. “But that’s okay. I think it’s better for us as physicians to police ourselves and accept the future rather than somebody coming from outside and doing it for us,” he added.

The guidelines surrounding nuclear stress testing were designed in a time before biochemical markers like troponin were widely used in the ED, Dr. Jaber explained. As such, he advocates for a revision of the guidelines and appropriate use criteria. Further changes might come if the use of high-sensitivity troponin—common in Europe—becomes more frequent in the United States, he added. At that point, he predicted, “the value of stressing these patients is going to become less and less important because [more sensitive biomarker testing] would be able to pick up any amount of myocardial ischemia.”

It would be ideal to see a trial designed in which ED patients from 5 or 6 hospitals receive almost every test—CK-MB, troponin, high-sensitivity troponin, and a stress test—to “figure out if there is an incremental value for each of these steps,” Dr. Jaber said. “We keep adding more and more tests, and we don’t know where they fit.”

 


Source:
Cremer PC, Khalaf S, Agarwal S, et al. Myocardial perfusion imaging in emergency department patients with negative cardiac biomarkers: yield for detecting ischemia, short-term events, and impact of downstream revascularization on mortality. Circ Cardiovasc Imaging. 2014;Epub ahead of print.

 

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Disclosures
  • Dr. Jaber reports no relevant conflicts of interest.

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