Characteristics and outcomes of cancelled STEMI activations following ECG analysis via a telemedicine application

The cancellation of STEMI alert patient transfers to the catheterization lab is common in STEMI networks. However, there is limited information on the outcomes of these patients and their short- and long-term prognosis.

This study aims to describe the clinical characteristics, the electrocardiographic patterns that prompted the activation, the final diagnosis, coronary angiographic findings, and both in-hospital and follow-up mortality of patients whose transfer to the catheterisation lab was cancelled.

We conducted a prospective registry of patients whose urgent transfer to the interventional unit was cancelled within a STEMI network from January 1, 2022, to October 1, 2023. Cancellations were made through a consensus decision facilitated by a telemedicine platform.

Among 882 patients with activated STEMI alerts, 337 (38.2%) had their transfers cancelled following a consensus decision. Table 1 presents the characteristics.

The mean age was 66 years, with 34.4% being female. The most common ECG patterns included ST elevation (30.3%), ST depression (23.1%), and left bundle branch block (13.6%). The two primary final diagnoses were acute coronary syndrome (ACS) (27%) and unspecified chest pain (23.1%), with other final diagnoses including aortic dissection (1.8%) and pulmonary embolism (1.5%). Coronary angiography was performed in 126 patients (37.4%); of these, 51 patients (40.4%) did not present coronary disease. Among those with coronary disease (75; 59.6%), TIMI 3 flow was observed in 101 (80.2%), while TIMI 0 flow was detected in 10 patients (3%), corresponding to acute occlusions that required urgent intervention. A total of 43.9% of patients were discharged directly from the emergency department. In-hospital mortality was 7.7%, and follow-up mortality reached 11.9% over an average period of 170 days.

Patients with cancelled STEMI alerts frequently present with alternative diagnoses, such as acute coronary syndrome and nonspecific chest pain, with 44% of patients discharged directly from the emergency department. However, 3% of these patients experienced undetected acute myocardial infarctions, highlighting potential errors in cancellation decisions.

The high in-hospital and follow-up mortality underscore the importance of precise ECG evaluation to avoid diagnostic errors. It also suggests that patients with cancelled alerts have a significant mortality risk, warranting close follow-up.

Table 1

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