Could Computed Tomography Coronary Angiography Replace Invasive Coronary Angiography as a First-Line Diagnostic Investigation in Suspected Acute Coronary Syndromes? A Decision-Analytic Model

BACKGROUND

The implementation of high-sensitivity cardiac troponin (hs-cTn) assays into clinical practice has resulted in the identification of a novel cohort of patients with modestly increased troponin concentrations. Subsequent increases in rates of coronary angiography have been observed, without significant increases in rates of coronary revascularisation. Computed tomography coronary angiography (CTCA) is a non-invasive investigation that offers the opportunity to decouple investigation from the impetus to revascularise, and may provide an alternative, more risk-appropriate initial investigative strategy for the cohort with low to moderate hs-cTn increases. This analysis seeks to define the threshold of pre-test probability of coronary revascularisation in patients with suspected acute coronary syndrome at which a strategy of initial CTCA is safe and a more cost-effective approach than standard invasive coronary angiography (ICA).

METHODS

A cost-benefit evaluation was conducted using a decision-analytic model. The primary outcome measure was the incremental cost-effectiveness ratio (ICER) of CTCA in comparison with ICA as an initial diagnostic investigation for patients with hs-cTnT levels between 5 and 100 ng/L. Secondary outcome measures of costs, patient outcomes, and quality-adjusted life years were analysed.

RESULTS

Median base case ICER over 1,000 trials was $17,163 AUD but demonstrated large variability. Sensitivity analysis demonstrated that CTCA was cost-effective until the probability of requiring revascularisation was ∼60%, beyond which point CTCA was associated with higher costs and poorer outcomes than ICA.

CONCLUSIONS

Computed tomography coronary angiography may be a cost-effective first-line investigation for patients with moderate hs-cTnT rises until/up to a 60% pre-test probability for receiving coronary revascularisation. To objectively assess the optimal circumstances of cost-effectiveness, prospective evaluation incorporating the estimated probability of revascularisation will be required.

Impacts of high sensitivity troponin T reporting on care and outcomes in clinical practice: Interactions between low troponin concentrations and participant sex within two randomized clinical trials

BACKGROUND

The impacts of high sensitivity cardiac troponin (hs-cTn) reporting on downstream interventions amongst suspected acute coronary syndrome (ACS) in the emergency department (ED), especially amongst those with newly identified hs-cTn elevations and in consideration of well-established sex-related disparities, has not been critically evaluated to date. This investigation explores the impact of hs-cTnT reporting on care and outcomes, particularly by participant sex.

METHODS

Two similarly ED-based randomized controlled trials conducted between July 2011 to March 2013 (n = 1988) and August 2015 to April 2019 (n = 3378) were comparatively evaluated. Clinical outcomes were adjudicated to the Fourth Universal Definition of MI. Changes in practice were assessed at 30 days, and death or MI were explored to 12 months.

RESULTS

The HS-Troponin study demonstrated no difference in death or MI with unmasking amongst those with hs-cTnT <30 ng/L, whereas the RAPID TnT study demonstrated a significantly higher rate. In RAPID TnT, there was significant increase in death or MI associated with unmasking for females with hs-cTnT <30 ng/L (masked: 11[1.5%], unmasked: 25[3.4%],HR: 2.27,95%C.I.:1.87-2.77,P < 0.001). Less cardiac stress testing with unmasking amongst those <30 ng/L was observed in males in both studies, which was significant in RAPID TnT (masked: 92[12.0%], unmasked: 55[7.0%], P = 0.008). In RAPID TnT, significantly higher rates of angiography in males were observed with unmasking, with no such changes amongst females <30 ng/L (masked: 28[3.7%], unmasked: 51[6.5%],P = 0.01).

CONCLUSION

Compared with males, there were no evident impacts on downstream practices for females with unmasking in RAPID TnT, likely representing missed opportunities to reduce late death or MI.

Sodium-Glucose Cotransporter 2 Inhibitors in South Australia: The Magic Before the Fame

BACKGROUND

Recent clinical trials have demonstrated that sodium-glucose cotransporter 2 inhibitors (SGLT2i), which were previously only indicated in treatment of type 2 diabetes mellitus (T2DM), can markedly reduce heart failure hospitalisation (HFH), with less striking potential reductions in acute coronary syndromes and cardiac arrhythmias. To evaluate the impact of SGLT2i on cardiovascular outcomes in real-world practice, we performed a retrospective cohort analysis on South Australian (SA) data.

METHODS

A total of 842 individuals with T2DM receiving SGLT2i were identified from SA public hospitals between 2011 and 2019. Episodes of care were temporally matched with those of 3,128 individuals with T2DM not receiving SGLT2i (control). Baseline characteristics were adjusted using inverse probability treatment weighting. The incidence of cardiovascular events at 12 and 24 months was evaluated using coded (International Classification of Diseases, Tenth Revision, Australian Modification [ICD-10-AM]) data.

RESULTS

The primary outcome of HFH was lower with SGLT2i use at 12 months (adjusted hazard ratio [HRadj] 0.44; 95% confidence interval [CI] 0.29-0.68; p<0.001) and 24 months. There were also lower hospitalisations due to acute myocardial infarction (HRadj 0.42; 95% CI 0.21-0.85; p=0.015) and atrial or ventricular arrhythmias (HRadj 0.29; 95% CI 0.14-0.59; p=0.001), with no difference observed in hospitalisation due to ischaemic cerebrovascular events. There was no difference in all-cause mortality at 12 months but interestingly a higher rate at 24 months (HRadj 2.08; 95% CI 1.59-2.72; p<0.001). Despite this, similar reductions in cardiovascular outcomes were observed at 24 months.

CONCLUSION

Use of SGLT2i in patients with T2DM in SA was associated with reductions in cardiovascular events even before their recent Pharmaceutical Benefits Scheme (PBS) listing for heart failure. Furthermore, this analysis supports that SGLT2i play a role not only in HFH reduction but also in reducing coronary and tachyarrhythmic events. This real-world evidence supports the use of SGLT2i as broadly protective cardiovascular drugs.

Twelve-Month Outcomes of Patients With Myocardial Injury not Due to Type-1 Myocardial Infarction

BACKGROUND

Diagnosis of acute myocardial infarction (AMI) requires a combination of elevated cardiac troponins, and clinical or echocardiographic evidence of coronary ischaemia. Identification of patients with a high likelihood of coronary plaque rupture (Type 1 myocardial infarction [MI]) is crucial as it is these patients for whom coronary intervention has been well-established to provide benefit and reduce subsequent coronary ischemic events. However, high-sensitivity cardiac troponin (hs-cTn) assays have increasingly identified patients with hs-cTn elevations not due to Type 1 MI where recommendations for ongoing care are currently limited. Understanding the profile and clinical outcomes for these patients may inform the development of an emerging evidence-base.

METHODS

Using two previously published studies (hs-cTnT study n=1,937, RAPID-TnT study n=3,270) and the Fourth Universal Definition of MI, index presentations of patients to South Australian emergency departments with suspected AMI, defined by high sensitivity cardiac troponin T (hs-cTnT) greater than the upper reference limit (14 ng/L) and without obvious corresponding ischaemia on electrocardiogram (ECG), were classified as either Type 1 MI (T1MI), Type 2 MI (T2MI), acute myocardial injury (AI), or chronic myocardial injury (CI). Patients with non-elevated hs-cTnT (defined as <14 ng/L) were excluded. Outcomes assessed included death, MI, unstable angina, and non-coronary cardiovascular events within 12 months.

RESULTS

In total, 1,192 patients comprising 164 (13.8%) T1MI, 173 (14.5%) T2MI/AI, and 855 (71.7%) CI were included. The rate of death or recurrent acute coronary syndrome was greatest in patients with T1MI, but also occurred with moderate frequency in Type 2 MI/AI and CI (T1MI: 32/164 [19.5%]; T2MI/AI: 24/173 [13.1%]; CI:116/885 [13.6%]; p=0.008). Of all the deaths observed, 74% occurred among those with an initial index diagnostic classification of CI. After adjusting for age, gender and baseline comorbidities, the relative hazard ratios for non-coronary cardiovascular readmissions were similar across all groups: Type 2 MI/AI: 1.30 (95% confidence interval 0.99-1.72, p=0.062); CI: 1.10 (95% confidence interval 0.61-2.00, p=0.75).

CONCLUSIONS

Non-T1MI accounted for the majority of patients presenting with elevated hs-cTnT without ischaemia on ECG. Patients with T1MI had the highest rates of death or recurrent AMI; however patients with T2MI/AI and CI experienced a substantial rate of non-coronary cardiovascular re-hospitalisations.

Contrasting the potential benefits of early invasive coronary angiography in acute and chronic myocardial injury patterns

BACKGROUND

In cases of evolving myocardial injury not definitively attributed to coronary ischaemia precipitated by plaque rupture, referral for invasive coronary angiography (ICA) may be influenced by observed troponin profiles. We sought to explore association between early ICA and elevated high-sensitivity troponin T (hs-cTnT) concentrations with and without dynamic changes, to examine if there may be a hs-cTnT threshold associated with benefit from an initial ICA strategy.

METHODS

Using published studies (hs-cTnT study n = 1937, RAPID-TnT study n = 3270) and the Fourth Universal Definition of Myocardial Infarction (MI), index presentations of patients with hs-cTnT concentrations 5-14ng/L were classified as 'non-elevated' (NE). Hs-cTnT greater than upper reference limit (14ng/L) were classified as 'elevated hs-cTnT with dynamic change' (encompassing acute myocardial injury, Type 1 MI, and Type 2 MI), or 'non-dynamic hs-cTnT elevation' (chronic myocardial injury). Patients with hs-cTnT <5ng/L and/or eGFR<15mmol/L/1.73m2 were excluded. ICA was performed within 30 days of admission. Primary outcome was defined as composite endpoint of death, MI, or unstable angina at 12 months.

RESULTS

Altogether, 3620 patients comprising 837 (23.1%) with non-dynamic hs-cTnT elevations and 332 (9.2%) with dynamic hs-cTnT elevations were included. Primary outcome was significantly higher with dynamic and non-dynamic hs-cTnT elevations (Dynamic: HR: 4.13 95%CI:2.92-5.82; p<0.001 Non-dynamic: HR: 2.39 95% confidence interval [CI]:1.74-3.28, p<0.001). Hs-cTnT thresholds where benefit from initial ICA strategy appeared to emerge was observed at 110ng/L and 50ng/L in dynamic and non-dynamic elevations, respectively.

CONCLUSION

Early ICA appears to portend benefit in hs-cTnT elevations with and without dynamic changes, and at lower hs-cTnT threshold in non-dynamic hs-cTnT elevation. Differences compel further investigation.

Implementation of more sensitive cardiac troponin T assay in a state-wide health service

AIMS

Explore the impact of deploying high-sensitivity (hs) cardiac troponin T (cTnT) assay across a state-wide health service.

METHODS AND RESULTS

Presentations to emergency departments of six tertiary hospitals between January 2008 and August 2019 were included; standard cTnT assay was superseded by hs-cTnT in June 2011 without changing the reference range (≥30 ng/L reported as elevated), despite cTnT level of 30 ng/L being equivalent to ∼44 ng/L with hs-cTnT. Clinical outcomes were captured using state-wide linked health records. Interrupted time series analyses were used adjusted for seasonality and multiple co-morbidities using propensity score matching allowing for correlation within hospitals. In total, 614,847 presentations had ≥1 troponin measurement. Clinical ordering of troponin decreased throughout the study with no increase in elevated measurements amongst those tested with hs-cTnT. Small but statistically significant changes in index myocardial infarction (MI) diagnosis (-0.36%/year, 95%CI [confidence interval]:-0.48, -0.24,p < 0.001) and invasive coronary angiography (0.12%/year,95%CI:0, 0.24,p = 0.02) were seen, with no impact on death/MI at 30 days or 3-year survival in episodes of care (EOCs) with elevated cTnT after hs-cTnT implementation. Length of stay (LOS) was shorter among those with an elevated hs-cTnT (-4.44 h/year, 95%CI:-5.27, -3.60, p < 0.001). Non-elevated cTnT EOCs demonstrated shorter total LOS and improved 3-year survival (adjusted hazard ratio:0.90, 95%CI:0.83, 0.97,p = 0.008) although death/MI at 30 days was unchanged using hs-cTnT.

CONCLUSION

Widespread implementation of hs-cTnT without altering clinical thresholds reported to clinicians provided significantly shorter LOS without a clinically significant impact on clinical outcomes. A safer cohort with non-elevated cTnT was identified by hs-cTnT compared to the standard cTnT assay.

Cost effectiveness of a 1-hour high-sensitivity troponin-T protocol: An analysis of the RAPID-TnT trial

•

This is the first randomised evaluation of the cost-effectiveness of a 0/1-hour high-sensitivity troponin protocol and has implications on clinical practice on a health system level.

•

The results demonstrate that the 0/1-hour hs-cTnT protocol is safe and does not incur excess resource compared to the conventional 0/3-hour protocol.

•

Whilst this cost-effectiveness analysis demonstrates superior ED efficiency and equivalent safety and resource associated with the 0/1-hour hs-cTnT protocol, further refinements in subsequent management is necessary to facilitate large-scale adaptation.

Background

To understand the economic impact of an accelerated 0/1-hour high-sensitivity troponin-T (hs-cTnT) protocol.

Objective

To conduct a patient-level economic analysis of the RAPID-TnT randomised trial in patients presenting with suspected acute coronary syndrome (ACS).

Methods

An economic evaluation was conducted with 3265 patients randomised to either the 0/1-hour hs-cTnT protocol (n = 1634) or the conventional 0/3-hour standard-of-care protocol (n = 1631) with costs reported in Australian dollars. The primary clinical outcome was all-cause mortality or new/recurrent myocardial infarction.

Results

Over 12-months, mean per patient costs were numerically higher in the 0/1-hour arm compared to the conventional 0/3-hour arm (by $472.49/patient, 95% confidence interval [95 %CI]: $-1,380.15 to $2,325.13, P = 0.617) with no statistically significant difference in primary outcome (0/1-hour: 62/1634 [3.8%], 0/3-hour: 82/1631 [5.0%], HR: 1.32 [95 %CI: 0.95–1.83], P = 0.100). The mean emergency department (ED) length of stay (LOS) was significantly lower in the 0/1-hour arm (by 0.62 h/patient, 95 %CI: 0.85 to 0.39, P < 0.001), but the subsequent 12-month unplanned inpatient costs was numerically higher (by $891.22/patient, 95 %CI: $-96.07 to 1,878.50, P = 0.077). Restricting the analysis to patients with hs-cTnT concentrations ≤ 29 ng/L, mean per patient cost remained numerically higher in the 0/1-hour arm (by $152.44/patient, 95 %CI:$-1,793.11 to $2,097.99, P = 0.988), whilst the reduction in ED LOS was more pronounced (by 0.70 h/patient, 95 %CI: 0.45–0.95, P < 0.001).

Conclusions

There were no differences in resource utilization between the 0/1-hour hs-cTnT protocol versus the conventional 0/3-hour protocol for the assessment of suspected ACS, despite improved initial ED efficiency. Further refinements in strategies to improve clinical outcomes and subsequent management efficiency are needed.

Classification performance of clinical risk scoring in suspected acute coronary syndrome beyond a rule-out troponin profile

AIMS

High-sensitivity cardiac troponin strategies can provide risk stratification in patients with suspected acute coronary syndrome (ACS) in the emergency department (ED). This study evaluated whether clinical risk scoring improves the classification performance of a rule-out profile in suspected ACS.

METHODS AND RESULTS

Patients presenting to ED with suspected ACS as part of the RAPID-TnT trial randomized to the intervention arm were included. Results ≥5 ng/L were available for all participants in this analysis. We evaluated the Thrombolysis In Myocardial Infarction (TIMI) risk score, History ECG Age Risk factors Troponin (HEART) score, and Emergency Department Assessment of Chest pain Score (EDACS) in addition to a rule-out profile based on the 0/1-h high-sensitivity cardiac troponin T protocol (<5 ng/L or ≤12 ng/L and a change of <3 ng/L at 1-h) using test performance parameters focusing on low-risk groups to identify the primary endpoint (TIMI ≤ 1, HEART ≤ 3, EDACS < 16). Primary endpoint was a composite of type 1/2 myocardial infarction (MI) at index presentation and all-cause mortality or type 1/2 MI at 30 days. A total of 3378 participants were enrolled between August 2015 and April 2019 of which 108 were ineligible/withdrew consent (intervention arm: n = 1638). Sensitivity, specificity, negative predictive value (NPV), and area under the curve (AUC) of the rule-out profile was 94.4%, 76.8%, 99.6%, and 0.86, respectively with 72.9% identified as 'low-risk'. Adding the clinical risk scores did not improve the sensitivity, NPV, or AUC with significantly lower specificity and 'low-risk' classified participants.

CONCLUSIONS

Addition of clinical risk scores to rule-out profile did not demonstrate improved classification performance for identifying the composite of type 1/2 MI at index presentation and all-cause mortality or type 1/2 MI at 30 days.

CLINICAL TRIALS REGISTRATION

URL: https://www.anzctr.org.au. Reg. No. ACTRN12615001379505.

Late Outcomes of the RAPID-TnT Randomized Controlled Trial: 0/1-Hour High-Sensitivity Troponin T Protocol in Suspected ACS

BACKGROUND

High-sensitivity troponin assays are increasingly being adopted to expedite evaluation of patients with suspected acute coronary syndromes. Few direct comparisons have examined whether the enhanced performance of these assays at low concentrations leads to changes in care that improves longer-term outcomes. This study evaluated late outcomes of participants managed under an unmasked 0/1-hour high-sensitivity cardiac troponin T (hs-cTnT) protocol compared with a 0/3-hour masked hs-cTnT protocol.

METHODS

We conducted a multicenter prospective patient-level randomized comparison of care informed by unmasked 0/1-hour hs-cTnT protocol (reported to <5 ng/L) versus standard practice masked hs-cTnT testing (reported to ≤29 ng/L) assessed at 0/3 hours and followed participants for 12 months. Participants included were those presenting to metropolitan emergency departments with suspected acute coronary syndromes, without ECG evidence of coronary ischemia. The primary end point was time to all-cause death or myocardial infarction using Cox proportional hazards models adjusted for clustering within hospitals.

RESULTS

Between August 2015 and April 2019, we randomized 3378 participants, of whom 108 withdrew, resulting in 12-month follow-up for 3270 participants (masked: 1632; unmasked: 1638). Among these, 2993 (91.5%) had an initial troponin concentration of ≤29 ng/L. Deployment of the 0/1-hour hs-cTnT protocol was associated with reductions in functional testing. Over 12-month follow-up, there was no difference in invasive coronary angiography (0/1-hour unmasked: 232/1638 [14.2%]; 0/3-hour masked: 202/1632 [12.4%]; P=0.13), although an increase was seen among patients with hs-cTnT levels within the masked range (0/1-hour unmasked arm: 168/1507 [11.2%]; 0/3-hour masked arm: 124/1486 [8.3%]; P=0.010). By 12 months, all-cause death and myocardial infarction did not differ between study arms overall (0/1-hour: 82/1638 [5.0%] versus 0/3-hour: 62/1632 [3.8%]; hazard ratio, 1.32 [95% CI, 0.95-1.83]; P=0.10). Among participants with initial troponin T concentrations ≤29 ng/L, unmasked hs-cTnT reporting was associated with an increase in death or myocardial infarction (0/1-hour: 55/1507 [3.7%] versus 0/3-hour: 34/1486 [2.3%]; hazard ratio, 1.60 [95% CI, 1.05-2.46]; P=0.030).

CONCLUSIONS

Unmasked hs-cTnT reporting deployed within a 0/1-hour protocol did not reduce ischemic events over 12-month follow-up. Changes in practice associated with the implementation of this protocol may be associated with an increase in death and myocardial infarction among those with newly identified troponin elevations. Registration: URL: https://www.anzctr.org.au; Unique identifier: ACTRN12615001379505.

Troponin elevation pattern and subsequent cardiac and non-cardiac outcomes: Implementing the Fourth Universal Definition of Myocardial Infarction and high-sensitivity troponin at a population level

Background

The Fourth Universal Definition of Myocardial Infarction (MI) differentiates MI from myocardial injury. We characterised the temporal course of cardiac and non-cardiac outcomes associated with MI, acute and chronic myocardial injury.

Methods

We included all patients presenting to public emergency departments in South Australia between June 2011–Sept 2019. Episodes of care (EOCs) were classified into 5 groups based on high-sensitivity troponin-T (hs-cTnT) and diagnostic codes: 1) Acute MI [rise/fall in hs-cTnT and primary diagnosis of acute coronary syndrome], 2) Acute myocardial injury with coronary artery disease (CAD) [rise/fall in hs-cTnT and diagnosis of CAD], 3) Acute myocardial injury without CAD [rise/fall in hs-cTnT without diagnosis of CAD], 4) Chronic myocardial injury [elevated hs-cTnT without rise/fall], and 5) No myocardial injury. Multivariable flexible parametric models were used to characterize the temporal hazard of death, MI, heart failure (HF), and ventricular arrhythmia.

Results

372,310 EOCs (218,878 individuals) were included: acute MI (19,052 [5.12%]), acute myocardial injury with CAD (6,928 [1.86%]), acute myocardial injury without CAD (32,231 [8.66%]), chronic myocardial injury (55,056 [14.79%]), and no myocardial injury (259,043 [69.58%]). We observed an early hazard of MI and HF after acute MI and acute myocardial injury with CAD. In contrast, subsequent MI risk was lower and more constant in patients with acute injury without CAD or chronic injury. All patterns of myocardial injury were associated with significantly higher risk of all-cause mortality and ventricular arrhythmia.

Conclusions

Different patterns of myocardial injury were associated with divergent profiles of subsequent cardiac and non-cardiac risk. The therapeutic approach and modifiability of such excess risks require further research.

A Randomized Trial of a 1-Hour Troponin T Protocol in Suspected Acute Coronary Syndromes: The Rapid Assessment of Possible Acute Coronary Syndrome in the Emergency Department With High-Sensitivity Troponin T Study (RAPID-TnT)

BACKGROUND

High-sensitivity troponin assays promise earlier discrimination of myocardial infarction. Yet, the benefits and harms of this improved discriminatory performance when incorporated within rapid testing protocols, with respect to subsequent testing and clinical events, has not been evaluated in an in-practice patient-level randomized study. This multicenter study evaluated the noninferiority of a 0/1-hour high-sensitivity cardiac troponin T (hs-cTnT) protocol in comparison with a 0/3-hour masked hs-cTnT protocol in patients with suspected acute coronary syndrome presenting to the emergency department (ED).

METHODS

Patients were randomly assigned to either a 0/1-hour hs-cTnT protocol (reported to the limit of detection [<5 ng/L]) or masked hs-cTnT reported to ≤29 ng/L evaluated at 0/3-hours (standard arm). The 30-day primary end point was all-cause death and myocardial infarction. Noninferiority was defined as an absolute margin of 0.5% determined by Poisson regression.

RESULTS

In total, 3378 participants with an emergency presentation were randomly assigned between August 2015 and April 2019. Ninety participants were deemed ineligible or withdrew consent. The remaining participants received care guided either by the 0/1-hour hs-cTnT protocol (n=1646) or the 0/3-hour standard masked hs-cTnT protocol (n=1642) and were followed for 30 days. Median age was 59 (49-70) years, and 47% were female. Participants in the 0/1-hour arm were more likely to be discharged from the ED (0/1-hour arm: 45.1% versus standard arm: 32.3%, P<0.001) and median ED length of stay was shorter (0/1-hour arm: 4.6 [interquartile range, 3.4-6.4] hours versus standard arm: 5.6 (interquartile range, 4.0-7.1) hours, P<0.001). Those randomly assigned to the 0/1-hour protocol were less likely to undergo functional cardiac testing (0/1-hour arm: 7.5% versus standard arm: 11.0%, P<0.001). The 0/1-hour hs-cTnT protocol was not inferior to standard care (0/1-hour arm: 17/1646 [1.0%] versus 16/1642 [1.0%]; incidence rate ratio, 1.06 [ 0.53-2.11], noninferiority P value=0.006, superiority P value=0.867), although an increase in myocardial injury was observed. Among patients discharged from ED, the 0/1-hour protocol had a negative predictive value of 99.6% (95% CI, 99.0-99.9%) for 30-day death or myocardial infarction.

CONCLUSIONS

This in-practice evaluation of a 0/1-hour hs-cTnT protocol embedded in ED care enabled more rapid discharge of patients with suspected acute coronary syndrome. Improving short-term outcomes among patients with newly recognized troponin T elevation will require an evolution in management strategies for these patients.

CLINICAL TRIAL REGISTRATION

URL: https://www.anzctr.org.au. Unique identifier: ACTRN12615001379505.

The appropriateness of coronary investigation in myocardial injury and type 2 myocardial infarction (ACT-2): A randomized trial design

BACKGROUND

Elevated troponin level findings among patients presenting with suspected acute coronary syndrome (ACS) or another intercurrent illness undeniably identifies patients at increased risk of mortality. Whilst enhancing our capacity to discriminate risk, the use of high-sensitivity troponin assays frequently identifies patients with myocardial injury (i.e. troponin rise without acute signs of myocardial ischemia) or type 2 myocardial infarction (T2MI; oxygen supply-demand imbalance). This leads to the clinically challenging task of distinguishing type 1 myocardial infarction (T1MI; coronary plaque rupture) from myocardial injury and T2MI in the context of concurrent acute illness. Diagnostic discernment in this context is crucial because MI classification has implications for further investigation and care. Early invasive management is of well-established benefit among patients with T1MI. However, the appropriateness of this investigation in the heterogeneous context of T2MI, where there is high competing mortality risk, remains unknown. Although coronary angiography in T2MI is advocated by some, there is insufficient evidence in existing literature to support this opinion as highlighted by current national guidelines.

OBJECTIVE

The objective is to evaluate the clinical and economic impact of early invasive management with coronary angiography in T2MI in terms of all-cause mortality and cost effectiveness.

DESIGN

This prospective, pragmatic, multicenter, randomized trial among patients with suspected supply demand ischemia leading to troponin elevation (n=1,800; T2MI [1,500], chronic myocardial injury [300]) compares the impact of invasive angiography (or computed tomography angiography as per local preference) within 5 days of randomization versus conservative management (with or without functional testing at clinician discretion) on all-cause mortality by 2 years. Randomized treatment allocation will be stratified by baseline estimated risk of mortality using the Acute Physiology, Age, and Chronic Health Evaluation (APACHE) III risk score. Cost-effectiveness will be evaluated by follow-up on clinical events, quality of life, and resource utilization over 24 months.

SUMMARY

Ascertaining the most appropriate first-line investigative strategy for these commonly encountered high-risk T2MI patients in a randomized comparative study will be pivotal in informing evidence-based guidelines that lead to better patient and health care outcomes.