1. In this randomized trial, diabetic patients with stable chest pain randomized to coronary computed tomographic angiography (CTA) had lower rates of cardiovascular death and myocardial infarction than those randomized to functional stress testing.
2. This benefit of the coronary CTA was not seen in nondiabetic patients.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Diabetes is one of the most common chronic diseases and a well-established cardiovascular risk factor. There has not been compelling data on an investigative strategy for diabetic patients with chest pain. In this randomized trial using data from PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain), diabetic patients randomized to coronary CTA compared with functional stress testing (nuclear imaging/stress echocardiogram/stress ECG) had lower rates of the composite outcome of cardiovascular death and myocardial infarction. This effect was not seen in non-diabetic patients. There was no difference in the composite outcome of death, myocardial infarction, and unstable angina hospitalization for diabetic or non-diabetic patients, although there was a trend towards improved outcome for diabetic patients randomized to coronary CTA for this outcome.
Although the randomized nature of this study and relatively balanced groups supports its conclusion, there are several limitations. Firstly, the sample size was small, with fewer than 2000 diabetic patients included in the final analysis. Secondly, 14% of the sample in the functional stress testing group and 9% of the sample in the coronary CTA group were lost to follow up.
In-Depth [ randomized controlled trial]: This study used data from PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain), a randomized trial evaluating coronary CTA versus functional stress testing in patients without known coronary disease who had symptoms consistent with stable coronary artery disease (CAD). Total sample size was 8,966 (1,908 with diabetes [21%] and 7,058 without [79%]). Median follow up was 25 months. Patients were randomized to coronary CTA or functional stress testing, which was the treating physician’s choice between exercise ECG, stress nuclear imaging, or stress echocardiogram. Inclusion criteria were age >55 for men or >65 for women, or age 45-54 with 1+ cardiovascular risk factor for men or age 55-64 with 1+ cardiovascular risk factor for women. Exclusion criteria included known history of CAD, non-interpretable non-invasive testing (NIT), unstable chest pain, or congenital/valvular/cardiomyopathic heart disease. Clinical outcomes of interest included time to death/myocardial infarction (MI)/unstable angina hospitalization (UAH) as well as cardiovascular death/MI. Patients with diabetes had similar demographics however more cardiovascular risk factors (hypertension, dyslipidemia, elevated body mass index (BMI)) compared with patients without diabetes.
Patients with diabetes had a higher rate of positive NIT compared to those without diabetes (15.2% vs 11.5%, adjusted OR 1.38, 95% CI 1.19 – 1.60, p<.001). This was consistent across all types of NIT. Of the 972 diabetic patients randomized to functional stress testing, 711 (73%) had nuclear scans, 185 (19%) had stress echocardiograms, and 76 (8%) had stress ECG. Patients randomized to coronary CTA had higher rates of referral to invasive coronary angiography as well as revascularization independent of diabetes status. Patients with diabetes had higher rates of death/MI/UAH (aHR 1.40, 95% CI 1.07-1.83, p=0.015) but similar risk of cardiovascular death/MI (aHR 1.35, 95% CI 0.91-1.99, p=0.131). Among patients with diabetes, those who underwent coronary CTA had non-significantly lower rates of death/MI/UAH (3.4% vs 4.4%, aHR 0.74, 95% CI 0.47 – 1.18, p=0.207) and significantly lower rates of cardiovascular death/MI (1.1% vs 2.6%, aHR 0.38, 95% CI 0.18-0.79, p=0.01).
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