Hyperacute T Wave in the Early Diagnosis of Acute Myocardial Infarction

STUDY OBJECTIVE

The diagnostic performance of T-wave amplitudes for the detection of myocardial infarction is largely unknown. We aimed to address this knowledge gap.

METHODS

T-wave amplitudes were automatically measured in 12-lead ECGs of patients presenting with acute chest discomfort to the emergency department within a prospective diagnostic multicenter study. The final diagnosis was centrally adjudicated by 2 independent cardiologists. Patients with left ventricular hypertrophy, complete left bundle branch block, or paced ventricular depolarization were excluded. The performance for lead-specific 95th-percentile thresholds were reported as likelihood ratios (lr), specificity, and sensitivity.

RESULTS

Myocardial infarction was the final diagnosis in 445 (18%) of 2457 patients. In most leads, T-wave amplitudes tended to be greater in patients without myocardial infarction than those with myocardial infarction, and T-wave amplitude exceeding the 95th percentile had positive and negative lr close to 1 or with confidence intervals (CIs) crossing 1. The exceptions were leads III, aVR, and V1, which had positive lrs of 3.8 (95% CI, 2.7 to 5.3), 4.3 (95% CI, 3.1 to 6.0) and 2.0 (95% CI, 1.4 to 2.9), respectively. These leads normally have inverted T waves, so T-wave amplitude exceeding the 95th percentile reflects upright rather than increased-amplitude hyperacute T waves.

CONCLUSION

Hyperacute T waves, when defined as increased T-wave amplitude exceeding the 95th percentile, did not provide useful information in diagnosing myocardial infarction in this sample.

Association of accompanying dyspnea with diagnosis and outcome of patients presenting with acute chest discomfort

AIM

The presence of accompanying dyspnea is routinely assessed and common in patients presenting with acute chest pain/discomfort to the emergency department (ED). We aimed to assess the association of accompanying dyspnea with differential diagnoses, diagnostic work-up and outcome.

METHODS

We enrolled patients presenting to the ED with chest pain/discomfort. Final diagnoses were adjudicated by independent cardiologists using all information including cardiac imaging. The primary diagnostic endpoint was the final diagnosis. The secondary diagnostic endpoint was the performance of high-sensitivity cardiac troponin (hs-cTn) and the European Society of Cardiology (ESC) 0/1h-algorithms for the diagnosis of myocardial infarction (MI). The prognostic endpoints were cardiovascular and all-cause mortality at two years.

RESULTS

Among 6045 patients, 2892/6045 (48%) had accompanying dyspnea. The prevalence of ACS in patients with versus without dyspnea was comparable (MI 22.4% vs. 21.9%, p = 0.60, unstable angina 8.7% vs. 7.9%, p = 0.29). In contrast, patients with dyspnea more often had cardiac, non-coronary disease (15.3% vs. 10.2%, p < 0.001). Diagnostic accuracy of hs-cTnT/I concentrations was not affected by the presence of dyspnea (area under the curve 0.89-0.91 in both groups) and the safety of the ESC 0/1h-algorithms was maintained with negative predictive values >99.4%. Accompanying dyspnea was an independent predictor for cardiovascular and all-cause death at two years (Hazard Ratio [HR] 1.813 [95%CI, 1.453-2.261, p < 0.01]).

CONCLUSION

Accompanying dyspnea was not associated with a higher prevalence of ACS but with cardiac, non-coronary disease. While the safety of the diagnostic work-up was not affected, accompanying dyspnea was an independent predictor for cardiovascular and all-cause death.

International Validation of the Canadian Syncope Risk Score : A Cohort Study

BACKGROUND

The Canadian Syncope Risk Score (CSRS) was developed to predict 30-day serious outcomes not evident during emergency department (ED) evaluation.

OBJECTIVE

To externally validate the CSRS and compare it with another validated score, the Osservatorio Epidemiologico della Sincope nel Lazio (OESIL) score.

DESIGN

Prospective cohort study.

SETTING

Large, international, multicenter study recruiting patients in EDs in 8 countries on 3 continents.

PARTICIPANTS

Patients with syncope aged 40 years or older presenting to the ED within 12 hours of syncope.

MEASUREMENTS

Composite outcome of serious clinical plus procedural events (primary outcome) and the primary composite outcome excluding procedural interventions (secondary outcome).

RESULTS

Among 2283 patients with a mean age of 68 years, the primary composite outcome occurred in 7.2%, and the composite outcome excluding procedural interventions occurred in 3.1% at 30 days. Prognostic performance of the CSRS was good for both 30-day composite outcomes and better compared with the OESIL score (area under the receiver-operating characteristic curve [AUC], 0.85 [95% CI, 0.83 to 0.88] vs. 0.74 [CI, 0.71 to 0.78] and 0.80 [CI, 0.75 to 0.84] vs. 0.69 [CI, 0.64 to 0.75], respectively). Safety of triage, as measured by the frequency of the primary composite outcome in the low-risk group, was higher using the CSRS (19 of 1388 [0.6%]) versus the OESIL score (17 of 1104 [1.5%]). A simplified model including only the clinician classification of syncope (cardiac syncope, vasovagal syncope, or other) variable at ED discharge-a component of the CSRS-achieved similar discrimination as the CSRS (AUC, 0.83 [CI, 0.80 to 0.87] for the primary composite outcome).

LIMITATION

Unable to disentangle the influence of other CSRS components on clinician classification of syncope at ED discharge.

CONCLUSION

This international external validation of the CSRS showed good performance in identifying patients at low risk for serious outcomes outside of Canada and superior performance compared with the OESIL score. However, clinician classification of syncope at ED discharge seems to explain much of the performance of the CSRS in this study. The clinical utility of the CSRS remains uncertain.

PRIMARY FUNDING SOURCE

Swiss National Science Foundation & Swiss Heart Foundation.

Incidence, characteristics, determinants, and prognostic impact of recurrent syncope

AIMS

The aim of this study is to characterize recurrent syncope, including sex-specific aspects, and its impact on death and major adverse cardiovascular events (MACE).

METHODS AND RESULTS

We characterized recurrent syncope in a large international multicentre study, enrolling patients ≥40 years presenting to the emergency department (ED) with a syncopal event within the last 12 h. Syncope aetiology was centrally adjudicated by two independent cardiologists using all information becoming available during syncope work-up and long-term follow-up. Overall, 1790 patients were eligible for this analysis. Incidence of recurrent syncope was 20% [95% confidence interval (CI) 18-22%] within the first 24 months. Patients with an adjudicated final diagnosis of cardiac syncope (hazard ratio (HR) 1.50, 95% CI 1.11-2.01) or syncope with an unknown aetiology even after central adjudication (HR 2.11, 95% CI 1.54-2.89) had an increased risk for syncope recurrence. Least Absolute Shrinkage and Selection Operator regression fit on all patient information available early in the ED identified >3 previous episodes of syncope as the only independent predictor for recurrent syncope (HR 2.13, 95% CI 1.64-2.75). Recurrent syncope carried an increased risk for death (HR 1.87, 95% CI 1.26-2.77) and MACE (HR 2.69, 95% CI 2.02-3.59) over 24 months of follow-up, however, with a time-dependent effect. These findings were confirmed in a sensitivity analysis excluding patients with syncope recurrence or MACE before or during ED evaluation.

CONCLUSION

Recurrence rates of syncope are substantial and vary depending on syncope aetiology. Importantly, recurrent syncope carries a time-dependent increased risk for death and MACE.

TRIAL REGISTRATION

BAsel Syncope EvaLuation (BASEL IX, ClinicalTrials.gov registry number NCT01548352).