Early diagnosis and risk stratification in patients with symptoms suggestive of acute coronary syndrome

<p>Background: Chest pain is one of the most common symptoms in patients presenting to the emergency department (ED). Identifying the minority of patients with an acute coronary syndrome (ACS) is a challenge. The introduction of high-sensitivity cardiac troponin (hs-cTn T and I) assays has radically improved the assessment. The aim of this thesis was to evaluate four methods of assessing patients presenting with suspected ACS in the era of hs-cTn.</p><p>Methods and results: In Study I, we retrospectively evaluated the value of predischarge exercise ECG testing in 951 chest pain patients in whom myocardial infarction (MI) had been ruled out by means of hs-cTnT. We found no significant differences regarding death or MI between patients with a positive or a negative test, neither at 90 (n=1 [1.1%] vs. n=1 [0.2%]), nor at 365 days (n=2 [2.1%] vs. n=4 [0.7%]) of follow-up. In total, there were 9 (0.9%) deaths and 10 (1.1%) MIs within 365 days. The one-year rates of death (1.3%) and MI (0.5%) in a matched Swedish population were comparable.</p><p>Study II was a retrospective evaluation of the diagnostic sensitivity of an undetectable level of hs-cTnT at presentation, with and without information from the electrocardiogram (ECG), to rule out MI in a non-ST-segment elevation MI (NSTEMI) population presenting early. Twenty-four (2.6%) of the 911 early presenting NSTEMI patients initially had an undetectable level of hs-cTnT. In patients presenting >1–≤2 hours from symptom onset, the sensitivity for MI when combining hs-cTnT and ECG was 99.4% (95% confidence interval [CI] 98.4%–99.8%). In patients presenting ≤1 hour from symptom onset and in patients aged ≤65 years without prior MI, the sensitivity was insufficient. NSTEMI patients presenting with an undetectable level of hs-cTnT were younger but had a similar 30-day outcome to NSTEMI patients presenting with a detectable level of hs-cTnT.</p><p>In Study III, we retrospectively evaluated a one-hour hs-cTnT algorithm in 1,091 chest pain patients with a non-elevated hs-cTnT when presenting to the ED and examined early dynamic changes in hs-cTnT. Dynamic one-hour changes (Δ ≥3 ng/L) occurred in 23 patients (2.1%). Fifteen patients (65.2%) in the dynamic group were admitted, compared to 148 patients (13.9%) in the non-dynamic group (p<0.001). Four of the patients admitted (26.7%) in the dynamic and one (0.7%) in the non-dynamic group were diagnosed with an MI (p<0.001). No death or MI occurred within 30 days among those discharged from the ED.</p><p>In Study IV, we evaluated the clinical effects of implementing a one-hour hs-cTnT or I algorithm combined with the HEART score in a prospective observational before-after study including 1,233 patients at six centres. The new strategy was associated with a reduction in admission rate (59% to 33%, p<0.001, adjusted odds ratio [95% CI]: 0.33 [0.25–0.42]), median time to discharge (23.2 to 4.7 hours, p<0.001) and median health care-related costs (€1,651 to €1,019, p<0.001). The rates of death and MI were very low.</p><p>Conclusions: Rapid hs-cTn algorithms improve the prognostic assessment in patients with suspected ACS, making routine admission and predischarge exercise ECG testing redundant.</p><h3>List of scientific papers</h3><p>I. Ljung L, Sundqvist M, Jernberg T, Eggers KM, Ljunggren G, Frick M. The value of predischarge exercise ECG testing in chest pain patients in the era of high-sensitivity troponins. European Heart Journal Acute Cardiovascular Care. 2018;7(3):278–84. <br><a href="https://doi.org/10.1177/2048872617690886">https://doi.org/10.1177/2048872617690886</a><br><br> </p><p>II. Ljung L, Reichard C, Hagerman P, Eggers KM, Frick M, Lindahl B, Linder R, Martinsson A, Melki D, Svensson P, Jernberg T. Sensitivity of undetectable level of high-sensitivity troponin T at presentation in a large non-ST-segment elevation myocardial infarction cohort of early presenters. [Submitted]</p><p>III. Pettersson A, Ljung L, Johansson C, Heilborn U, Jernberg T, Frick M, Eggers KM, Lindahl B, Linder R, Martinsson A, Svensson P. Experiences of a one-hour algorithm in chest pain patients with a non-elevated troponin T at presentation. Critical Pathways in Cardiology. 2018;17(1):6–12. <br><a href="https://doi.org/10.1097/HPC.0000000000000138">https://doi.org/10.1097/HPC.0000000000000138</a><br><br></p><p>IV. Ljung L, Lindahl B, Eggers KM, Frick M, Linder R, Löfmark HB, Martinsson A, Melki D, Sarkar N, Svensson P, Jernberg T. A rule-out strategy based on high-sensitivity troponin and HEART score reduces hospital admissions. [Submitted]</p>