Eletrocardiographic mapping nearing clinical utility

By Eleanor McDermid, Senior medwireNews Reporter

Electocardiographic mapping (ECM) may offer a noninvasive and accurate alternative to a standard electrophysiologic study (EPS), say researchers.

Ivan Cakulev (Harrington Heart and Vascular Institute, Cleveland, Ohio, USA) and colleagues say that ECM has been "almost entirely experimental" until now, with theirs the first demonstration of the technique in patients with a variety of rhythm disorders.

"Our experience described in this report suggests that the use of ECM is not only feasible, but is also highly accurate in describing abnormal cardiac activation," they write in Circulation: Arrhythmia and Electrophysiology.

The 27 patients in the study underwent computed tomography while wearing a vest containing 252 electrodes. With this approach, electrograms can be matched up to cardiac geometry, giving a 3D epicardial activation map than is more precise that that achievable with 12-lead electrocardiography.

When set against invasive EPS results, ECM identified the location of interest in 25 of the 27 patients. These included six patients with Wolff-Parkinson-White syndrome, 10 with atrial tachycardia/flutter, and one with sustained exercise-induced ventricular tachycardia.

ECM identified the ventricular chamber of origin and the earliest site of activation in eight of 10 patients with symptomatic premature ventricular complexes (PVCs), including four of six with PVCs originating from the ventricular outflow tract. The case was less clear for the other two patients; although the ECM findings were supported by the EPS results, ablation at the indicated site produced only transient suppression of the PVC.

"This may not be indicative of ECM inaccuracy, but rather could represent a problem with delivering adequate radiofrequency energy at the site correctly identified by invasive EPS and ECM," suggest Cakulev et al.

Notably, ECM identified the origin of the PVCs in a patient who had two simultaneous but disparate epicardial breakthroughs on both ventricles. "This type of diagnosis would have been much more difficult to deduce with conventional endocardial activation mapping," says the team.

The researchers say that a randomized trial will be necessary to fully define the benefits and drawbacks of ECM relative to other approaches.

But they conclude: "Nevertheless, our data demonstrate that ECM noninvasively provides very useful clinical information that can potentially be used to help plan invasive electrophysiological studies in patients."

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