Session S54.2

Ischemia Monitoring by Analysis of Depolarization Changes

G Amit, LR Davrath, S Abboud, H Hod,
E Toledo*, S Matetzky

Biological Signal Processing Ltd.
Tel Aviv, Israel

Background: Changes in the depolarization phase of the cardiac cycle, quantified using analysis of high-frequency QRS (HFQRS) components, has been previously reported to be a sensitive method for detection of demand ischemia. We introduce a novel HFQRS analysis technology for detection of transient ischemic episodes at rest. The aim of this study was to evaluate the performance of continuous HFQRS monitoring in detecting ischemia in patients hospitalized due to chest pain. Methods: 43 patients (56±10 yo, 31 men) admitted to a chest pain unit for observation, ST monitoring, biomarker retesting and cardiac imaging (SPECT, CCT, Echo and PCI) were continuously monitored (12.5±3 hours) by high-resolution 12-lead ECG (HyperQ™ System, BSP, Israel). Indices of HFQRS based on ischemia-specific morphological changes and conventional ST segment levels were extracted from signal-averaged ECG. Receiver operating characteristics (ROC) was used to determine cut-off values for HFQRS indices. Patients were stratified by the likelihood of experiencing ischemic events: high (positive imaging test), medium (negative imaging with high risk of acute coronary syndrome [ACS] by the ACC/AHA guidelines) and low (negative imaging with low or intermediate risk of ACS). The relation between the severity of the HFQRS indices and the likelihood of ischemic events was examined. Results: ST-segment analysis was negative for ischemic events in all 43 patients. Positive HFQRS indices were obtained in 5 of 10 patients with high likelihood of ischemia. HFQRS indices were negative in 7 of 9 pts with medium and 22 of 24 pts with low likelihood of ischemia. The area under the ROC curve was 0.75. The average number of positive HFQRS leads was directly related to the likelihood of ischemic events, increasing from 1.5±0.8 for the low-likelihood group to 2.6±1.3 for the high-likelihood group (p<0.005). Conclusions: HFQRS morphological indices are superior to conventional ST monitoring in detecting ischemic episodes, in patients hospitalized with chest pain. HFQRS analysis is a promising technology, which may aid in monitoring of transient ischemic episodes and early detection of acute coronary syndrome.

(Abstract Control Number: 18)