Early detection of Ischaemia Through High Frequency ECGs: The role of Medical-Grade Wearables for Chest Pain Triages

Electrocardiogram(ECG) represents the electrical activity of the heart. Currently approved routine ECGs with a bandwidth of 0.05 - 150Hz have a very low sensitivity (approx 48%) defined by the ST segment criteria for ischaemia. High-Frequency ECG (HF-ECG) Signals have been shown to have increased sensitivity and early timing in diagnosing cardiac ischaemia. Ischaemic changes happen first during contraction of the heart, causes disturbances in the higher frequencies in the QRS segments and are in microvolts in amplitude. Additionally, HF-ECG of Microvolts are buried in the Millivolts of QRS waves and are difficult to extract. Technical difficulties in extraction have made us discard this crucial data till now and instead accept ST segments as the gold standard for ischemia diagnosis. ST segments represent repolarisation in time domain where cardiac muscle is relaxed and may allow adequate perfusion hence has low accuracy. We present case studies here, one each in a normal and an ACS patient respectively with a portable high resolution ECG device called Sydantek from Carditek Medical Devices. The hardware details for data capture, the bandpass filters, extraction methods and display are described in this early case reports. The defining features in HF- ECG extraction are described. Our findings confirm the utility of this portable device for possible use in acute emergencies . This device may be most relevant in emergency room settings for chest pain triages and in post angioplasty evaluations once larger trials confirm these findings.