Coronary CTA triages ER chest pain patients safely, inexpensively

Cardiac CTA has matched the clinical safety of a standard emergency room protocol for triaging chest pain patients with suspected myocardial infarction while cutting costs by more than a third in a multicenter randomized clinical trial involving more than 700 patients.

Dr. Kavitha Chinnaiyan, a cardiologist at William Beaumont Hospital in Royal Oak, MI, described the results of the 16-center Coronary Computed Tomography Angiography for Systematic Triage of Acute Chest Pain Patients to Treatment (CT-STAT) trial Nov. 25 at the 2009 American Heart Association meeting in Orlando, FL.

The trial examined the clinical and cost experiences of  low-risk chest pain patients who received either a standard ER protocol including rest-stress myocardial perfusion or an alternative workup featuring coronary CTA.

The results confirmed what numerous single-center studies of coronary CTA have shown. Because of its ability to rule out significant coronary artery disease with greater than 95% certainty, coronary CTA is well-suited clinically for assessing patient who appear in the ER with acute chest pain but have normal electrocardiograms and cardiac enzymes at their initial evaluations.

And it also reaps a financial bonus. Patients who underwent coronary CTA typically spent half as much time under observation as patients who received the standard workup. And the coronary CTA evaluation cost 38% less, which translates to a median $1321 savings.

Patients were randomized to CT or a standard workup, according to Chinnaiyan. In the CT arm, normal findings or the presence of minimal disease led to patient discharge. A finding of severe disease (one or more sites of 70% or greater stenosis) led to referral for immediate cardiac catheterization. Patients with intermediate disease (25% to 75% stenosis in at least one segment) or whose scan was uninterpretable underwent rest-stress myocardial perfusion imaging. Patients were discharged if the nuclear stress test was normal.

In the standard protocol group, patients underwent rest-stress SPECT. Patients with abnormal findings were referred for catheterization. Patients with normal findings were discharged, she said.

In the CT arm, no significant stenosis was found in 297 of 361 (82.3%) of the patients. Of these, 262 patients were discharged after coronary CTA, with a median time to discharge of 5.4 hours after admission. At least one significant stenosis (greater than 70%) was found in 27 (7.3%) patients. Twenty-four patients underwent invasive angiography. This procedure led to intervention for nine patients and surgery for four patients.

Moderate stenosis was found in the remaining 37 patients. Of that number, 14 patients had nondiagnostic scans.

For patients who received the routine standard of care, myocardial perfusion imaging was normal in 306 of 340 (90%) patients. Most were discharged immediately. Two patients with abnormal myocardial perfusion scans were discharged at physician discretion.

Myocardial perfusion imaging was abnormal or equivocal in 34 (10%) patients. Eight underwent coronary CTA. For 21 patients, invasive angiography was performed.

No difference was identified between the two groups in the percentage of patients referred for invasive angiography (6.9% versus 6.2%), Chinnaiyan said. No surgical revascularizations were performed on patients in the standard protocol group.

In terms of diagnostic efficiency, the median time to diagnosis for patients in the coronary CTA arm was 2.9 hours, 53% less time than the 6.2 hours of observation for patients receiving the standard workup.

The median cost to diagnose in the standard protocol arm was $3458. In the CT arm, it was $2137, a reduction of 38%, Chinnaiyan said.

The percentage of patients who had acute coronary syndrome was similar for both groups: 11% for patients receiving coronary CT and 10% for patients who underwent the standard protocol. In six months after the evaluations, no one in either trial arm had a major adverse cardiac event.

"Compared with the standard of care (conventional protocol), CTA as a primary diagnostic imaging strategy in acute chest pain patients is equally safe, faster, and cheaper," Chinnaiyan said.