Session S74.3

Heart-Rate Adaptive Match Filter Based Procedure to Detect and Quantify T-Wave Alternans

L Burattini*, R Burattini

Polytechnic University of Marche
Ancona, Italy

T-wave alternans (TWA) is an important, non-invasive indicator of risk of sudden cardiac death. Thus, development of methods for automatic detection and quantification of TWA has been a major challenge in the last two decades. Recently, we proposed a new time-domain approach, based on a heart-rate adapting match filter (AMF). Compared to methods for detecting TWA reported by others, our AMF-based procedure (AMFP) does not require pre-processing of the digital ECG and allows straight-forward identification and quantification of transient, beyond sustained, TWA. Our AMF, in fact, filters out not only noise and baseline wandering, but also any other ECG component but the TWA. The aim of the present study was to test our AMFP on the PhysioNet/Computers in Cardiology Challenge 2008 database, containing 100 multichannel recordings from healthy subjects and patients affected by various risk factors (myocardial infarction, transient ischemia, ventricular tachyarrhythmias, etc.). Our AMF was first applied to each ECG of the database for detection and parameterization of TWA in terms of duration (TWAD), amplitude (TWAA), and magnitude (TWAM, defined as TWAD times TWAA). Based on these parameters, a statistical threshold criterion was, then, applied to discriminate between noise-ascribable TWA and risk TWA (TWA+). In the absence of information on challenge database healthy subjects, we used threshold levels derived from 35 healthy subjects of our own database. Twenty recordings were rejected by our AMFP for too high heart-rate (RR<525 msec; 17 cases), or noise level (3 cases). Preliminary results on the other 80 recordings, characterized 16 cases as TWA+ (TWAD=79±13 beats; TWAA=111±69 microV; TWAM=8417±5659 beats microV). Our preliminary reference challenge-ranking was 0.605. Although our AMF algorithm can be modified to detect TWA in most rejected tracings, the physiological interpretation of TWA when heart-rate approaches tachycardia is an open issue. Relation between detected TWA+ cases, as provided by our AMFP, and clinical outcome of the patients will be possible after this outcome is made available.

(Abstract Control Number: 375)