Photo Credit: Nutjaree Yomjun
This study demonstrated that the four-variable formula, applied to serial electrocardiograms in patients with subtle anterior myocardial infarction, exhibited high sensitivity, specificity, and overall diagnostic accuracy, emphasizing its effectiveness in distinguishing between ST-elevation myocardial infarction and benign variant ST-segment elevation.
The following is a summary of “Usefulness of the four-variable formula on serial electrocardiograms in detecting subtle anterior myocardial infarction,” published in the November 2023 issue of Emergency Medicine by Sert, et al.
For a study, researchers sought to conduct electrocardiogram (ECG) evaluations in patients showcasing subtle ECG alterations in the anterior leads. They aimed to assess the efficacy of a four-variable formula in identifying left anterior descending (LAD) coronary artery occlusion.
The prospective study was conducted between April 2021 and January 2023, focusing on patients admitted to the emergency department due to acute chest discomfort. These patients initially exhibited ECG readings that were not conclusively indicative but raised suspicions of myocardial infarction (MI). Subsequently, these patients underwent percutaneous coronary intervention as part of their treatment. The control group, on the other hand, comprised patients diagnosed with benign variant ST-segment elevation (BV-STE). The criteria for this group included ST-segment elevation (STE) of a minimum of 1 mm in the anterior lead, normal cardiac troponin levels, and the presence of non-cardiac chest pain. Post-admission, a total of six ECGs were administered at 10-minute intervals. Using these serial ECGs, the four-variable formula scores were computed and juxtaposed between the patient groups for comparison.
The study encompassed 232 patients, evenly divided between those diagnosed with anterior MI and those with BV-STE. Utilizing a threshold of ≥18.2 for the four-variable formula, the initial ECG exhibited a sensitivity, specificity, and overall diagnostic accuracy of 82.7%, 85.3%, and 83.6%, respectively. Notably, the ECG captured at the 20-minute mark showcased the highest sensitivity (83.6%), specificity (89.6%), and diagnostic accuracy (86.2%) in detecting LAD occlusions based on the four-variable formula.
The study underscored the efficacy of the four-variable formula as a reliable tool for discerning between STEMI and BV-STE in patients manifesting subtle ECG alterations. For clinicians managing this patient cohort, employing serial ECG evaluations, as opposed to relying on a singular ECG, can enhance the precision of clinical decision-making processes.
Source: sciencedirect.com/science/article/abs/pii/S0735675723004503
