Combining qualitative and quantitative ECG criteria with the ESC 0/1h-hs-cTn-algorithm in the early diagnosis of non-ST-elevation myocardial infarction
Authors: Lopez Ayala P , Boeddinghaus J , Nestelberger T , Strebel I , Koechlin L , Rubini Gimenez M , Wildi K , Twerenbold R , Mueller C 
Published: October 2022

Abstract

Background
The electrocardiogram (ECG) is one of the three main diagnostic tools for the assessment of patients with suspected non-ST-elevation myocardial infarction (NSTEMI). However, it is unknown how established qualitative or novel quantitative ECG criteria can best be combined with high-sensitivity cardiac troponin (hs-cTn)-based diagnostic algorithms, such as the ESC 0/1h-algorithm, for the early diagnosis of NSTEMI.

Methods
ST-segment depression, T-wave inversion, and a novel modified ST-segment deviation score (1), defined as the sum of ST-segment elevation in aVR plus absolute, unsigned ST-segment depressions in the remaining leads, were assessed blinded to all clinical data among unselected patients presenting with acute chest discomfort to the emergency department in an international multicentre prospective diagnostic study. Final diagnoses were centrally adjudicated by two independent cardiologists based on complete cardiac work-up, cardiac imaging and serial hs-cTn. Direct rule-in thresholds for the modified ST-segment deviation score, achieving a positive predictive value (PPV) of &gt;70% justifying early monitorization and management, were derived, validated and compared to ST-segment depression and T-wave inversion and applied 1) alone and 2) in combination with the ESC 0/1h-hs-cTnT/I-algorithms.

Results
Among 3299 eligible patients, NSTEMI was present in 581 (17.6%) patients. ST-segment depression identified 243/3299 patients (7.4%) with a specificity of 96.5% (95% CI 95.7–97.1) and a PPV of 60.5% (95% CI 54.2–66.4) for the rule-in of NSTEMI, while T-wave inversion had a low PPV (38.0%; 95% CI 33.1–43.1). A modified ST-segment deviation score ≥6mm triaged 108/3299 patients (3.3%) towards direct rule-in upon ED arrival, resulting in a PPV of 71.3% (95% CI 62.1–79.0) and a specificity of 98.9% (95% CI 98.4–99.2), Figure 1. Bootstrap internal validation confirmed the robustness of these findings. Most patients ruled-in by ST-segment depression or a modified ST-segment deviation score ≥6mm would have been also ruled-in by the ESC 0/1h-hs-cTnT/I-algorithm, albeit 1–2h later. Combining ST-segment depression or a modified ST-segment deviation score ≥6mm with the ESC 0/1h-hs-cTnT-algorithm (Figure 2) accelerated the rule-in in those identified already by the ECG-criteria, and resulted in a modest number of reclassifications from rule-out or observe to rule-in. These results were confirmed in a secondary analysis assessing the combination of these ECG signatures with two ESC 0/1h-hs-cTnI-algorithms (Architect and Centaur).

Conclusion
Combining either ST-segment depression or a modified ST-segment deviation Score ≥6mm with the ESC 0/1h-hs-cTnT/I-algorithms accelerated and improved the early diagnosis of NSTEMI.

Funding Acknowledgement
Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Swiss Heart Foundation (SHF) and Swiss National Science Foundation (SNSF)