Most hospitals in the United States have yet to transition from conventional to high-sensitivity cardiac troponin (hs-cTn) assays, despite their greater sensitivity for myocardial injury, a new National Cardiovascular Data Registry (NCDR) registry study indicates.
hs-cTn assays have been used in routine clinical practice in Europe, Canada, and Australia since 2010, but the first such assay did not gain approval in the US until 2017. Although single-center studies have examined their efficacy and potential downstream consequences, few data exist on hs-cTn implementation nationally, explained study author Cian McCarthy, MB, Bch, BAO, Massachusetts General Hospital, Boston.
The results were published online in the Journal of the American College of Cardiology and will be formally presented November 5 at the American Heart Association 2022 Scientific Sessions.
For the study, McCarthy and colleagues examined 550 hospitals participating in the NCDR Chest Pain-MI registry from January 2019 through September 2021.
Of the 251,000 patients included in the analysis (mean age, 64 years; 41.5% female), 155,049 had a non–ST-segment myocardial infarction (NSTEMI), 15,989 had unstable angina, and 79,962 had low-risk chest pain.
The hs-cTn assays included Roche Diagnostic’s Elecsys Gen5 STAT troponin T assay (23%); Abbott’s ARCHITECT STAT (17%); Beckman Coulter’s ACCESS (21%); and Siemens’ Atellica IM (18%), Dimension VISTA (14%), Dimension EXL (4%), and ADVIA Centaur (2%) troponin I assays.
During the study period, 11.5% of patients were evaluated with hs-cTn assays and the remainder were evaluated with conventional troponin assays. These patients were slightly older (65.0 vs 64.0 years), more commonly white (83.1% vs 79.9%), less likely to be of Hispanic or Latino ethnicity (8.9% vs 10.0%), and less likely to be uninsured (6.8% vs 8.3%; P for all < .001).
A slightly higher proportion of patients evaluated with hs-cTn assays were diagnosed with unstable angina (7.1% vs 6.3%), a lower proportion with NSTEMI (61.1% vs 61.9%), and a similar proportion with low-risk chest pain (31.8% vs 31.9%) compared with those evaluated by conventional troponin assays.
Implementation, defined as at least 25% of patients evaluated by hs-cTn in each quarter, increased from 3.3% in the first quarter of 2019 to 32.6% in the third quarter of 2021 (P trend < .001).
Using higher implementation thresholds of at least 50% and 75% of patients evaluated by hs-cTn, the prevalence in 2021 was 28.9% and 24.7%, respectively.
“So still, the majority of the hospitals by the end of the third quarter 2021 were not using these assays,” McCarthy said.
Potential explanations for the slow uptake are that prospective comparative effectiveness trials of hs-cTn assays have predominantly been in international populations and real-world data on US implementation have been limited to integrated health networks at academic institutions.
Approval of several assays was also delayed and the study data cut off just before the October publication of the 2021 AHA/ACC Chest Pain guideline. “So, whether the chest pain guideline with the new class 1 recommendation for hs-cTn will lead to further uptake is something that will need to be looked at in the future,” he said.
Downstream Testing
In adjusted analyses, hs-cTn use was associated with more echocardiography among patients with NSTE-acute coronary syndrome (NSTE-ACS) (82.4% vs 75.0%; odds ratio [OR], 1.43; 95% CI, 1.19-1.73), but not among those with low-risk chest pain (19.7% vs 19.4%; OR, 0.93; 95% CI, 0.71-1.22) compared with conventional cTn assays.
Importantly, hs-cTn was not associated with a difference in stress testing or CT coronary angiography utilization.
hs-cTn use was associated with lower use of invasive coronary angiography among patients with low-risk chest pain (3.7% vs 4.5%; OR, 0.73, 95% CI, 0.58-0.92) but similar use for NSTE-ACS (96.3% vs 95.8%; OR, 0.99, 95% CI, 0.82-1.19).
Among patients with NSTE-ACS, there also was no difference in revascularization with percutaneous coronary intervention (PCI) (52.7% vs 52.3%; OR, 0.99; 95% CI, 0.94-1.04) or coronary bypass graft surgery (9.4% vs 9.1%; OR, 1.06; 95% CI, 0.94-1.18).
PCI (0.1% vs 0.2%; P = .05) and bypass graft surgery (both 0.1%) were uncommon among patients with low-risk chest pain.
In-hospital mortality was similar among patients with low-risk chest pain evaluated using hs-cTn assays vs conventional troponin assays (0% vs 0.02%; P = .16) and among patients with NSTE-ACS (2.8% vs. 3.2%; OR, 0.98, 95% CI, 0.87-1.11).
Length of stay was slightly shorter with hs-cTn use for patients with low-risk chest pain (median, 5.8 vs 6.2 hours; P < .001) and patients with NSTE-ACS (66.9 vs 67.8 hours; P = .01).
“There was always a concern that maybe high-sensitivity cardiac troponin would dramatically increase testing and could even increase length of stay, but I think these data are reassuring, in that this study suggests high-sensitivity cardiac troponin is associated with a small reduction in length of stay and possibly more appropriate use of testing with echocardiography in STEMI and a reduction in invasive angiography in low-risk patients,” McCarthy said. “But the majority of hospitals haven’t implemented the assay.”
The authors point out that because registry entry of patients with low-risk chest pain and unstable angina is optional for participating sites, the percentage of patients with NSTEMI is higher than in typical chest pain analyses. This higher pretest probability for MI may thus affect post-test accuracy for a true positive result. “That stated, this is the exact scenario where higher sensitivity might be associated with favorable impact on utilization.”
Other limitations include the potential for unmeasured confounders, the accuracy of diagnoses could not be confirmed, patients with type 2 MI are excluded from the registry, and post-discharge safety was not assessed.
“These data indicate further opportunities to more widely and effectively implement hs-cTn in the U.S. hospitals persist that could optimize care for patients with possible or definitive ACS,” McCarthy and colleagues conclude.
The study was funded by the American College of Cardiology’s National Cardiovascular Data Registry. McCarthy is supported by the NHLBI and has received consulting income from Abbott Laboratories.
J Am Coll Cardiol. Published online October 31, 2022. Abstract
American Heart Association Scientific Sessions 2022. To be presented November 5, 2022.
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