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Imaging-Guided Strategy vs. Routine Care for NSTEMI Patients
Study Questions:
What is the utility of a novel strategy incorporating either cardiovascular magnetic resonance imaging (CMR) or computed tomographic angiography (CTA) first in the diagnostic pathway of patients with high-sensitivity cardiac troponin T (hs-cTnT) positive acute chest pain patients?
Methods:
The investigators conducted a randomized controlled trial in 207 patients (mean age 64 years; 62% male patients) with acute chest pain, elevated hs-cTnT levels (>14 ng/L), and inconclusive electrocardiogram (ECG) and compared a CMR- or CTA-first strategy with a control strategy of routine clinical care. Follow-up invasive coronary angiography (ICA) was recommended when initial CMR or CTA suggested myocardial ischemia, infarction, or obstructive coronary artery disease (CAD) (≥70% stenosis). Primary efficacy and secondary safety endpoints were referral to ICA during hospitalization and 1-year outcomes (major adverse cardiac events [MACE] and complications), respectively. Kaplan-Meier plots were computed to evaluate the cumulative incidence of clinical outcome over time. Differences in the cumulative incidence between groups were compared with the log-rank test and the Cox proportional hazards regression model.
Results:
The CMR- and CTA-first strategies reduced ICA compared with routine clinical care (87% [p = 0.001], 66% [p < 0.001], and 100%, respectively), with similar outcome (hazard ratio, CMR vs. routine, 0.78 [95% confidence interval, 0.37-1.61]; CTA vs. routine, 0.66 [95% confidence interval, 0.31-1.42]; and CMR vs. CTA, 1.19 [95% confidence interval, 0.53-2.66]). Obstructive CAD after ICA was found in 61% of patients in the routine clinical care arm, in 69% in the CMR-first arm (p = 0.308 vs. routine), and in 85% in the CTA-first arm (p = 0.006 vs. routine). In the non-CMR and non-CTA arms, follow-up CMR and CTA were performed in 67% and 13% of patients and led to a new diagnosis in 33% and 3%, respectively (p < 0.001).
Conclusions:
The authors concluded that a novel strategy of implementing CMR or CTA first in the diagnostic process in non–ST-segment elevation myocardial infarction (NSTEMI) is a safe gatekeeper for ICA.
Perspective:
This small study reports that a diagnostic strategy incorporating CMR or CTA first in patients with acute chest pain or its equivalent, an inconclusive ECG, and elevated hs-cTnT levels (i.e., NSTEMI) safely reduces the number of ICAs compared with routine clinical care. Furthermore, this approach led to a more appropriate selection of patients sent for ICA in comparison with routine clinical care, in which greater than one-third of patients did not have obstructive CAD. Of note, a trend of decreased MACE and complications was observed in the CMR- and CTA-first strategies compared with routine clinical care suggesting no detrimental effect on clinical outcome. Additional large multicenter trials with hard clinical endpoints are needed to confirm the effectiveness, generalizability, safety, and value of an imaging-guided diagnostic strategy.
Keywords: Acute Coronary Syndrome, Chest Pain, Constriction, Pathologic, Coronary Angiography, Coronary Artery Disease, Coronary Stenosis, Diagnostic Imaging, Electrocardiography, Magnetic Resonance Imaging, Myocardial Infarction, Secondary Prevention, Tomography, X-Ray Computed, Troponin T
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