SMARTwatch for the Diagnosis of ST-segment Elevation Myocardial Infarction in Patients With Chest Pain (SMART-CART-AMI)

Background and Rationale:

The clinical spectrum of acute coronary syndrome (ACS) is broad, with chest pain being the primary symptom initiating the diagnostic and therapeutic cascade. In patients with ST-segment elevation myocardial infarction (STEMI), immediate reperfusion -primarily via percutaneous coronary intervention (PCI)-is crucial. While primary PCI has significantly reduced mortality, minimizing systemic delays remains vital.

Recently, wearable devices with electrocardiographic (ECG) capabilities have emerged as potential tools for ultra-early cardiac triage. Previous research, such as the SMARTAMI study, demonstrated that a sequential 9-lead smartwatch ECG has high sensitivity and specificity for detecting STEMI. However, these prior studies often compared confirmed myocardial infarction cases with healthy, asymptomatic cohorts in highly controlled environments. There is a critical need to validate the technical feasibility, signal quality, and diagnostic accuracy of this technology in a real-world Emergency Department (ED) setting with unselected patients, where factors like diaphoresis, acute pain, and time urgency complicate the recording process.

Study Design and Clinical Procedures:

This is a prospective, observational diagnostic validation and concordance study conducted in a real-world clinical setting. Patients evaluated by the on-call cardiologist for ischemic-profile chest pain will be consecutively enrolled. The study is purely observational; obtaining the smartwatch ECG will not delay standard clinical care, and standard medical management will remain unaltered.

Following standard protocols, an analog sequential 9-lead ECG (I, II, III, V1-V6) will be recorded using a smartwatch alongside the standard 12-lead ECG.

Blinding and Data Evaluation:

A rigorous double-blind, independent analysis will be performed. The on-call cardiologists responsible for acquiring the tracings in the ED will not participate in their interpretation. Both the standard 12-lead ECGs and the smartwatch ECGs will be completely anonymized using unique alphanumeric codes. Subsequently, independent expert cardiologists will blindly evaluate the tracings, classifying them as "STEMI" or "non-STEMI" without any knowledge of the patient's clinical data or the origin of each specific recording.

Statistical Approach and Sample Size:

Based on prior literature in controlled settings reporting a 93% sensitivity, this real-world study conservatively estimates an 85% expected sensitivity due to ED-specific variables (e.g., signal noise, diaphoresis). To achieve a 10% margin of error with a 95% confidence level, a sample size of 49 confirmed STEMI positive cases is required. Consecutive recruitment will continue uninterrupted until this target is reached. Patients enrolled during this period who are ultimately diagnosed as "non-STEMI" will be retained in the database to calculate the specificity of the device.