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18-11-2009 | Cardiology | Article

CT-STAT: CTA faster and cheaper than standard protocol for CAD diagnosis

Abstract

Meeting website

MedWire News: A protocol using initial computed tomography angiography (CTA) is effective and both faster and cheaper than standard-of-care (SOC) evaluation in the diagnosis of coronary artery disease (CAD) among low-to-intermediate risk patients with chest pain, show results of the CT-STAT trial.

Time to diagnosis was halved while costs decreased by a third using a strategy including CTA compared with SOC in this trial, which was presented at the American Heart Association annual scientific sessions in Orlando, Florida, USA.

Presenting the study findings at a press conference, Kavitha Chinnaiyan (William Beaumont Hospital, Royal Oak, Michigan, USA) explained that in the USA alone nearly 6 million people present to emergency centers with acute chest pain. About 4–13% of who will have a missed diagnosis of myocardial infarction (MI), and among this group the mortality is high at around 20–25%.

This has caused “huge litigation issues,” Chinnaiyan continued, accounting for 20% of emergency room malpractice dollars. Consequently an extensive rule-out MI protocol has been developed to reduce diagnostic error, but this is time consuming and resource intensive.

CT-STAT (Computed Tomographic Angiography for the Systematic Triage of Acute Chest Pain Patients to Treatment) tested whether using CTA, which earlier studies have shown has high negative predictive accuracy (around 95–99%) for ruling out CAD, is safe and could provide time and cost reductions in diagnosis compared with a standard evaluation protocol.

CT-STAT included 749 patients with negative initial cardiac enzyme and electrocardiogram results. Patients were randomly assigned to receive a diagnostic strategy including CTA (n=376) or SOC with myocardial perfusion imaging (n=373) for disposition to immediate discharge, additional noninvasive testing, or invasive angiography.

In the CTA arm, no significant stenosis was found in 297 (82.3%) patients, of whom 262 (72.6%) were discharged immediately. At least one significant stenosis (>50%) was found in 27 (7.5%) patients and invasive angiography performed in 24 (6.7%) patients. Eleven patients were revascularized, nine underwent percutaneous coronary intervention (PCI), and four underwent coronary artery bypass graft (CABG).

A further 23 (9%) had moderate stenosis and CT was uninterpretable in 14 patients.

In the SOC arm, MPI was normal in 306 (90.0%) of patients, and 304 (89.4%) were discharged immediately. MPI was abnormal or equivocal in 34 (10%) patients and eight patients crossed over to undergo CTA.

Invasive angiography was performed in 21 (6.2%) patients, a similar proportion to that in the CTA arm, of whom eight underwent PCI, and none underwent CABG.

Results showed that the primary safety outcome of freedom from 6-month major adverse cardiac events (MACE) was the same in each group, with no patients having MACE in either.

For the primary efficiency outcome, time to diagnosis was 6.2 hours versus 2.9 hours (53% relative reduction, p<0.0001) and emergency department costs US $3458 (€2328) versus $2137 (€1439) in the CT versus SOC arm (38% relative reduction, p<0.001).

Robert Bonow (Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA) discussed the trial at a Late Breaking Clinical Science session at the conference.

Noting that key remaining questions include how reproducible the findings will be in a larger number of centers, what the optimal radiation doses should be, and how the CT strategy might impact long-term outcomes, Bonow said the findings “support the development of larger scale, longer-term trials assessing cardiovascular events, downstream procedures, and resource utilization.”

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2009

By Caroline Price

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