Inpatient Mortality and 30-Day Readmission Rates Associated with Troponin Testing in Patients without Acute Myocardial Infarction

OBJECTIVE

Troponin values above the threshold established to diagnose acute myocardial infarction (AMI; >99th percentile) are commonly detected in patients with diagnoses other than AMI. The objective of this study was to compare inpatient mortality and 30-day readmission rate in patients with troponin I (TnI) above and below the 99th percentile in those with type 1 AMI and type 2 myocardial injury.

METHODS

Between January 1, 2016 and December 31, 2016, there were 56,895 inpatient hospitalizations; of these 14,326 (25.2%) patients received troponin testing. We evaluated mortality and readmissions in the entire cohort based on the primary discharge International Classification of Diseases, Tenth Edition (ICD-10) diagnosis and grouped into type 1 AMI versus other diagnoses comprising the type 2 AMI group (including ICD-10 codes for congestive heart failure, sepsis, and other). Among those with TnI drawn, we evaluated in-hospital mortality and 30-day readmissions based on troponin values > 99th percentile (≥ 0.1 ng/ml).

RESULTS

Among the entire cohort, the inpatient mortality rate was significantly higher in those with TnI testing (5.0%, 95% CI 4.6%-5.3%) compared to those without testing (0.7%, 95% CI 0.6%-0.7%, P < 0.01). In the tested cohort 3,743 (26%) patients had troponin levels above the 99th percentile (> 0.1 ng/ml), and 10,583 (74%) had troponin levels below the 99th percentile (≤ 0.1 ng/ml). Comparing type 2 AMI with type 1 AMI and troponin testing, TnI values ≥ 0.1 ng/ml were associated with higher inpatient mortality (11.6% vs. 3.9%) and 30-day readmission rates (16.9% vs. 10.7%).

CONCLUSIONS

A higher inpatient mortality and 30-day readmission rates were found in patients with type 2 AMI compared to type 1 AMI group.

Implications of Misclassification of Type 2 Myocardial Infarction on Clinical Outcomes

BACKGROUND

Patients with type 2 myocardial infarction (MI) are often classified under the diagnosis of non-ST-segment-elevation MI (NSTEMI) despite the significant differences in clinical characteristics, management, and outcomes between type 2 MI and type 1 NSTEMI. This may have significant implications that can lead to inaccurate assessment of quality measures by MI quality review programs.

METHODS

A single-center retrospective study of 1224 patients discharged with the diagnosis of type 1 NSTEMI between January 2015 and September 2017. Based on the third universal definition of MI, we stratified patients into type 2 MI or type 1 NSTEMI. Patient's characteristics, comorbidities, medications prescribed during hospitalization and at discharge, readmissions within 30 days after discharge, and diagnostic and therapeutic interventions data was collected. The primary goal of this study was to identify how often type 2 MI patients were misclassified as type 1 NSTEMI, we also assessed the differences in treatment and outcomes between type 2 MI and type 1 NSTEMI.

RESULTS

1224 patients assigned the ICD-9 and ICD-10 codes of type 1 NSTEMI at discharge were evaluated for study inclusion. After application of the inclusion criteria, 945 patients were included in the final analysis. Of these 945 patients, 281 (29.7%) patients were classified as type 2 MI and 664 (70.3%) patients were classified as type 1 NSTEMI. Patients with type 2 MI were older, more likely to have systolic heart failure, had lower peak troponin levels, were less likely to receive aspirin, P2Y12 inhibitors and statin at discharge, and had longer length of stay. Compared with type 1 NSTEMI patients, those with type 2 MI had higher all cause 30-day mortality (13.5% versus 2.9%, P < 0.0001) (RR: 4.65; 95% CI, 2.85-9.65). After adjusting for patient demographics, comorbidities, and medications, patients with type 2 MI were still more likely to die within 30 days after discharge (RR: 2.89; 95% CI, 1.58-7.46). In addition, patients with type 2 MI were more likely to be readmitted within 30 days after discharge than patients with type 1 NSTEMI (17.7% versus 13.9%, P < 0.01) (RR: 1.27; 95% CI, 1.08-2.5).

CONCLUSIONS

Close to one third of patients given the diagnosis of type 1 NSTEMI at discharge at our institution were type 2 MI patients. Patients with type 2 MI are managed differently from type 1 NSTEMI patients and have higher 30-day mortality and readmission rate. Misclassification of type 2 MI as type 1 NSTEMI can have a significant impact on hospitals MI clinical performance and quality measures.

Suspected ACS Patients Presenting With Myocardial Damage or a Type 2 Myocardial Infarction Have a Similar Late Mortality to Patients With a Type 1 Myocardial Infarction: A Report From the Australian and New Zealand 2012 SNAPSHOT ACS Study

BACKGROUND

Cardiac troponin (T and I) are considered the standard markers for detection of myocardial damage and the diagnosis of acute coronary syndrome (ACS) among patients who present to an emergency department with chest pain. However, these markers can be released in other situations and may be associated with short- and long-term clinical outcomes. In this study, we examine late mortality rates among patients presenting with a suspected ACS due to an unstable coronary plaque and those patients having a non-ACS.

METHODS

4388 patients were hospitalised with suspected ACS, between 14 and 27 May 2012 in the Australia and New Zealand SNAPSHOT ACS study. Those patients were categorised in five diagnostic groups: 1) ST elevation MI (n=419); 2) non-ST elevation MI (n=1012); 3) unstable angina (n=925); 4) non-ACS diagnoses (n=837); and 5) chest pain considered unlikely ischaemic (not otherwise specified, n=1195).

RESULT

The respective mortality rates at 18 months in these groups were 16.2%, 16.3%, 6.8%, 12.8%, and 4.8%; Pearson χ²=110 p<0.001. Among non-ACS diagnoses patients (group 4) those with the highest mortality rates (cardiac (14.4%), respiratory (18.2%), sepsis (15.4%) and neoplastic (67%) diagnoses) had the highest rates of elevated troponin levels (48%, 31%, 38% and 67% respectively). By contrast, those with the lowest mortality rates (musculoskeletal (2.9%), gastrointestinal disorders (3.9%) and non-specific chest pain (7.4%)) had the lowest rate of elevated troponin levels (9%, 18% and 15.8% respectively). However, after adjusting for baseline clinical and demographic characteristics, the mortality rate at 18 months for patients with elevated troponin was similar for ACS or non-ACS diagnoses (Hazard Ratio, 95% C.I.0.98-1.07, p=0.333).

CONCLUSIONS

Among patients in the 2012 SNAPSHOT ACS study, non-ACS diagnoses characterised by high rates of elevated troponin levels had high mortality rates similar to those diagnosed with ACS. Therapies known to be effective in ACS patients, including early invasive management, should be examined in these non-ACS patients with troponin elevations within adequately powered randomised trials.

Multiple Chronic Conditions in Older Adults with Acute Coronary Syndromes

Older adults presenting with acute coronary syndromes (ACSs) often have multiple chronic conditions (MCCs). In addition to traditional cardiovascular (CV) risk factors (ie, hypertension, hyperlipidemia, and diabetes), common CV comorbidities include heart failure, stroke, and atrial fibrillation, whereas prevalent non-CV comorbidities include chronic kidney disease, anemia, depression, and chronic obstructive pulmonary disease. The presence of MCCs affects the presentation (eg, increased frequency of type 2 myocardial infarctions [MIs]), clinical course, and prognosis of ACS in older adults. In general, higher comorbidity burden increases mortality following MI, reduces utilization of ACS treatments, and increases the importance of developing individualized treatment plans.