14th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 2000

Jan. 29 - Feb. 5, 2000
Marilleva, Trento, Italy

RT-29

Computerized Holter monitoring: a comprehensive noninvasive electrophysiological test for the identification of patients at high risk of ventricular arrhythmias

Emanuela Locati Heilbron.
Cattedra di Cardiologia e Fisiopatologia Cardiovascolare, Dipartimento di Medicina Clinica, Patologia e Farmacologia, Universita degli Studi di Perugia, Ospedale Silvestrini, Perugia, Italy

Sudden cardiac death (SCD) due to life-threatening arrhythmias is a leading cause of cardiovascular mortality in the European Countries. Effective diagnostic methods to identify patients at high risk for SCD are still missing. Nowadays, patients at risk of SCD are generally evaluated by intracardiac electrical stimulation, an expensive and invasive method. The challenge is to develop new broadly used noninvasive and low-cost methods that will allow the identification of high-risk patients before they experience a major arrhythmic event.

Recent improvements in digital Holter technology have increased the accuracy of software-based analysis systems. Also, better signal quality and greater capability of arrhythmia interpretation have increased potential uses for ambulatory electrocardiography¹.

Lately, several new noninvasive markers associated with increased propensity to life-threatening cardiac arrhythmias have been derived from noninvasive 24-hour Holter monitoring. The most promising noninvasive index of elevated risk for SCD is low heart rate variability, measured by time- and frequency-domain analysis, powerful independent risk factors for cardiac mortality and sudden death in several different cardiac conditions^2,3.

More recently, research in risk stratification has been focused on the increased duration and dispersion of ventricular repolarization, assessed on the surface ECG by the so-called “QT interval”^4,5. Very recent studies are focusing on temporal heterogeneity of ventricular repolarization (defined as “T wave alternans”, TWA), which is now considered as a new promising index of elevated risk for SCD. However, so far TWA analysis is restricted to short-term ECG recorded during exercise stress test or atrial pacing, and it has not been implemented on routine long-term ECG Holter monitoring technique yet.

The positive predictive value of each noninvasive index alone is generally too low to be sufficient to take decisions about clinical prognosis and therapeutic management. So far, those indexes have never been combined in a comprehensive noninvasive electrocardiographic (ECG) test, to fully characterize the electrical substrate that may lead to SCD.

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