Reliable exclusion of acute coronary syndrome among hospitalized patients with elevated troponin

Prevalence of left ventricular systolic dysfunction by single echocardiographic view: towards an evidence-based point of care cardiac ultrasound scanning protocol

Limited views are often obtained in the setting of cardiac ultrasound, however, the likelihood of missing left ventricular (LV) dysfunction based on a single view is not known. We sought to determine the echo views that were least likely to miss LV systolic dysfunction in consecutive transthoracic echocardiograms (TTEs). Structured data from TTEs performed at 2 hospitals from September 25, 2017, to January 15, 2019, were screened. Studies of interest were those with reported LV dysfunction. Views evaluated were the parasternal long-axis (PLAX), parasternal-short axis at mitral (PSAX M), papillary muscle (PSAX PM), and apical (PSAX A) levels, apical 2 (AP2), apical 3 (AP3), and apical 4 (AP4) chamber views. The probability that a view contained at least 1 abnormal segment was determined and analyzed with McNemar's test for 21 adjusted pair-wise comparisons. There were 4102 TTE studies included for analysis. TTEs on males comprised 72.7% of studies with a mean LV ejection fraction of 42.8 ± 9.7%. The echo view with the greatest likelihood of encompassing an abnormal segment was the AP2 view with a prevalence of 93.4% (p < 0.001, compared to all other views). The PLAX view performed the worst with a prevalence of 82.5% (p < 0.015, compared to all other views). The best parasternal view for the detection of abnormality was the PSAX PM view at 90.4%. In conclusions, a single echo view will contain abnormal segments > 82% of the time in the setting of LV systolic dysfunction, with a prevalence of up to 93.4% in the apical windows.

Causes of Troponin Elevation and Associated Mortality in Young Patients

BACKGROUND

While increased serum troponin levels are often due to myocardial infarction, increased levels may also be found in a variety of other clinical scenarios. Although these causes of troponin elevation have been characterized in several studies in older adults, they have not been well characterized in younger individuals.

METHODS

We conducted a retrospective review of patients 50 years of age or younger who presented with elevated serum troponin levels to 2 large tertiary care centers between January 2000 and April 2016. Patients with prior known coronary artery disease were excluded. The cause of troponin elevation was adjudicated via review of electronic medical records. All-cause death was determined using the Social Security Administration's death master file.

RESULTS

Of the 6081 cases meeting inclusion criteria, 3574 (58.8%) patients had a myocardial infarction, while 2507 (41.2%) had another cause of troponin elevation. Over a median follow-up of 8.7 years, all-cause mortality was higher in patients with nonmyocardial infarction causes of troponin elevation compared with those with myocardial infarction (adjusted hazard ratio [HR] 1.30; 95% confidence interval [CI], 1.15-1.46; P < .001). Specifically, mortality was higher in those with central nervous system pathologies (adjusted HR 2.21; 95% CI, 1.85-2.63; P < .001), nonischemic cardiomyopathies (adjusted HR 1.66; 95% CI, 1.37-2.02; P < .001), and end-stage renal disease (adjusted HR 1.36; 95% CI, 1.07-1.73; P = .013). However, mortality was lower in patients with myocarditis compared with those with an acute myocardial infarction (adjusted HR 0.43; 95% CI:, 0.31-0.59; P < .001).

CONCLUSION

There is a broad differential for troponin elevation in young patients, which differs based on demographic features. Most nonmyocardial infarction causes of troponin elevation are associated with higher all-cause mortality compared with acute myocardial infarction.

Prognostic implications of low level cardiac troponin elevation using high-sensitivity cardiac troponin T

BACKGROUND

High-sensitivity cardiac troponin T (hsTnT) is used in many countries, but is not available in the United States. Prior evidence has been viewed as inconclusive as to whether low cardiac troponin T (cTnT) concentrations detected with hsTnT are prognostically meaningful compared with fourth-generation cTnT.

HYPOTHESIS

The aim of this study was to assess the prognostic performance of low-level cTnT elevations using the hsTnT assay compared with the assay (fourth-generation) currently available in the United States.

METHODS

We measured serum cTnT in 4160 patients with non-ST-elevation acute coronary syndrome using both the hsTnT and fourth-generation assays. Patients were stratified at the 99th percentile cut point for each assay.

RESULTS

Patients with baseline hsTnT ≥14 ng/L (n = 3697) vs <14 ng/L were at higher 30-day risk of cardiovascular death (CVD) or myocardial infarction (MI) (9.1% vs 1.9%, P < 0.0001). After adjusting for all other elements of the Thrombolysis In Myocardial Infarction risk score, hsTnT ≥14 carried a 5.2-fold higher risk of CVD/MI (95% confidence interval [CI]: 2.6-10.1, P < 0.0001). Low levels of hsTnT (14-50 ng/L) also revealed increased risk (CVD/MI: 6.4%, P = 0.002). Importantly, patients with negative fourth-generation cTnT but positive hsTnT were at 4.5-times higher risk of CVD/MI (95% CI: 1.9-11.0, P = 0.0008) than patients with negative hsTnT. In contrast, patients with a negative hsTnT but positive fourth-generation cTnT result had a lower rate of CVD/MI than with a positive hsTnT (1.3% vs 8.2%, P = 0.0005).

CONCLUSIONS

Low-level increases in cTnT detected using the hsTnT assay identified patients at a meaningfully higher risk and who might otherwise be missed, and improves upon risk stratification using the cTnT assay currently available in the United States.