The evaluation of patients with acute chest pain is a challenging clinical task. Standard testing is often non-conclusive, and the consequences of a missed diagnosis can be severe. Despite a low threshold to hospital admission, of whom the vast majority turns out not to have an acute coronary syndrome, still a small number of patients are inappropriately discharged from the emergency ward. For these reasons the care of acute chest pain patients are a logistic and financial burden to the healthcare system. Immediate non-invasive coronary angiography by cardiac CT holds promise as a means to effectively exclude an acute disease. However, previous observational studies, including the ROMICAT study [Hoffmann, J Am Coll Cardiol. 2009], have shown that the interpretation of the cardiac CT scan is not straightforward under these circumstances. In addition, there is virtually no prospective data on the logistic and economic performance in comparison to alternative tests in the evaluation of acute chest pain.
In a multicenter, clinical trial in 16 emergency departments nearly 700 low-risk patients were randomized between contrast-enhanced cardiac CT (CCT) and stress/rest SPECT myocardial perfusion imaging (MPI) as the index non-invasive test. CCT found no or minimal coronary artery disease in 82% of patients (73% of total immediately discharged), intermediate disease in 10%, and severe obstructive disease in 10%, while only 4% was regarded non-interpretable. MPI was normal in 90%, and 80% could be discharged immediately. CT resulted in a 54% reduction in time to diagnosis (from randomization till test result) compared with MPI: 2.9h vs. 6.3h (p < 0.0001), which reduced the cost of care in the emergency ward from US$3,458 to US$2,137, a 38% reduction. There were very few major adverse events (myocardial infarction, unstable angina, cardiac death and revascularizations) in both groups: 0.8% for CCT vs. 0.4% for MPI (p = 0.29). Patients with low calcium scores or less than 25% obstructive disease could be sent home safely. The authors conclude that in low-risk acute chest pain CCTA results in an equally safe, but more rapid and cost-efficient diagnosis than rest-stress MPI.
This study is groundbreaking as one of the first multicenter randomized trial to examine the incremental value of cardiac CT in patients with acute chest pain. Both CT and MPI were shown to be equally safe, but with logistic advantages for CCT. Although there was a non-significant trend towards fewer immediate discharges, more secondary testing, CCT was less expensive, mostly because it could be performed faster. As the authors conclude the results of the present study are limited to low-risk patients with chest pain, without a previous history of CAD and in the absence of contraindications to CT (recruitment rate 11%). The logistic and economic advantages may vary depending on the local setting, did not include downstream management, and may be smaller using contemporary SPECT equipment and protocols (without rest acquisitions), as Michael Salerno and colleagues comment in an accompanying editorial. Finally, what constitutes standard care in low-risk acute chest pain varies around the globe. Whether CCT maintains it’s logistic and economic advantage in comparison in different settings has yet to be investigated. Although substantial tasks lie ahead, the CT-STAT investigators are to be complemented for this important step towards clinical validation of cardiac CT in the setting of acute chest pain.
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