ACC.15: SCOT-HEART–Coronary CTA and Nailing the Diagnosis of Coronary Heart Disease
abstract
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The benefit of CT coronary angiography (CTCA) in patients presenting with stable chest pain has not been systematically studied. We aimed to assess the effect of CTCA on the diagnosis, management, and outcome of patients referred to the cardiology clinic with suspected angina due to coronary heart disease.
Methods
In this prospective open-label, parallel-group, multicentre trial, we recruited patients aged 18–75 years referred for the assessment of suspected angina due to coronary heart disease from 12 cardiology chest pain clinics across Scotland. We randomly assigned (1:1) participants to standard care plus CTCA or standard care alone. Randomisation was done with a web-based service to ensure allocation concealment. The primary endpoint was certainty of the diagnosis of angina secondary to coronary heart disease at 6 weeks. All analyses were intention to treat, and patients were analysed in the group they were allocated to, irrespective of compliance with scanning.
Findings
Between Nov 18, 2010, and Sept 24, 2014, we randomly assigned 4146 (42%) of 9849 patients who had been referred for assessment of suspected angina due to coronary heart disease. 47% of participants had a baseline clinic diagnosis of coronary heart disease and 36% had angina due to coronary heart disease. At 6 weeks, CTCA reclassified the diagnosis of coronary heart disease in 558 (27%) patients and the diagnosis of angina due to coronary heart disease in 481 (23%) patients (standard care 22 [1%] and 23 [1%]; p<0·0001). Although both the certainty (relative risk [RR] 2·56, 95% CI 2·33–2·79; p<0·0001) and frequency of coronary heart disease increased (1·09, 1·02–1·17; p=0·0172), the certainty increased (1·79, 1·62–1·96; p<0·0001) and frequency seemed to decrease (0·93, 0·85–1·02; p=0·1289) for the diagnosis of angina due to coronary heart disease. This changed planned investigations (15% vs 1%; p<0·0001) and treatments (23% vs 5%; p<0·0001) but did not affect 6-week symptom severity or subsequent admittances to hospital for chest pain. After 1·7 years, CTCA was associated with a 38% reduction in fatal and non-fatal myocardial infarction (26 vs 42, HR 0·62, 95% CI 0·38–1·01; p=0·0527), but this was not significant.
Interpretation
In patients with suspected angina due to coronary heart disease, CTCA clarifies the diagnosis, enables targeting of interventions, and might reduce the future risk of myocardial infarction.
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Additional Info
Disclosure statements are available on the authors' profiles:
The SCOT-HEART study tested whether computed tomography coronary angiography (CTA) improved the evaluation and management of low- to intermediate-risk patients with suspected angina due to coronary heart disease (CHD). The primary endpoint—the diagnosis of angina due to CHD—was evaluated in two domains. The first “certainty” was assessed as whether CTA would improve the number of patients who would have a clear "yes" or "no" diagnosis compared with “probable” or “unlikely." The second domain, “frequency” of the diagnosis was determined by proportion of patients in whom the diagnosis was “yes” or “probable.”
In contrast to the PROMISE study,1 which directly compared CTA with an exercise tolerance testing–based strategy, the SCOT-HEART study allowed all patients to undergo exercise ECG testing if indicated, and then randomized 4621 patients to either CTA plus standard of care or standard of care alone. After 6 weeks, the primary endpoint (diagnosis) was assessed by the attending clinician based on the totality of clinical data, including the CTA.
CTA significantly improved the certainty of the diagnosis of symptomatic CHD (yes or no) compared with standard of care in 1 in 4 patients. CTA increased the overall frequency of the diagnosis of CHD, but lowered the frequency of cases in which the diagnosis of angina was due to CAD. In other words, it helped identify more nonobstructive disease while making it more likely “rule-out” symptomatic CAD, presumably in patients without CHD on CTA.
A CTA-based strategy did not affect short-term anginal symptoms, although it significantly altered the subsequent diagnostic testing and treatments. CTA increased the overall rates of revascularization, and, in an underpowered analysis, demonstrated a trend toward fewer cardiovascular events, an observation not seen in the larger PROMISE study.
PROMISE and SCOT-HEART both evaluated the role of CTA in the evaluation of suspected symptomatic CHD. While the strategies and comparators were different, the results are, in general, consistent. CTA is a good diagnostic test, in particular to establish more definitively if a patient does or does not have epicardial coronary stenosis. A strategy of using CTA is likely to increase the number of subsequent catheterizations, although the rate of “true positive” will be higher, and lead to more revascularizations. A CTA-guided strategy, though, does not appear to significantly improve clinical outcomes.
Reference
Investigators randomized 4000 patients with angina suspected to be related to coronary disease to standard of care and standard of care plus CT coronary angiography (CTCA).1 The diagnosis was found to be more certain in the CTCA group, and more patients were reclassified.
The CTCA results changed the planned investigations (15% vs 1%) and the treatments (23% vs 5%). After the CTCA, 121 patients had their stress tests cancelled, and there were only 5 new cases for stress testing. Medical therapies were cancelled in 189 patients and started in 375. CTCA helped clinicians more accurately diagnose patients, which affected the tests and the treatments that patients ultimately received.
Myocardial infarction and cardiovascular death were reduced by 38% (P = .0527), so just barely significant, but this is still important especially given that follow-up in the study was only 1.7 years on average. The conclusion is that CTCA is a useful tool for our patients with angina.
The second study was just published comparing CTCA (anatomic testing) vs functional testing (exercise electrocardiograph, nuclear stress, stress echo).2 The PROMISE study involved 10,000 patients and results showed that both CTCA and functional testing had equal outcomes. There was no benefit of one strategy over the other. However, more patients in the CCTA group subsequently went onto catheterization (12.2% vs 8.1%). The radiation dose was also slightly higher in the CTCA group (12.0 mSv vs 10.1 mSv). The main exposure in the functional testing group was from the nuclear stress testing.
Taken together, the outcomes of both studies indicate that CTCA is a useful tool, but the other tools that test functional status are also useful. CTCA may be easier for the patient, and it is less time-consuming, despite a bit more radiation; CTCA might be a more efficient method to triage our patients with coronary artery disease. Unfortunately neither study captured the difficulty or time involved in performing the tests either for the patients or for the facilities. For now, all the tests are considered good and the key is to use them properly for our patients.
References