Case
Cardiac resynchronization therapy (CRT) improves survival by paced pre-excitation of the lateral /posterolateral LV1. This patient with a history of anterior and anterolateral wall LV infarction (LV ejection fraction 10%, end- diastolic internal diameter 8.2 cm) improved two functional classes (NYHA IV to II) within 4 weeks of CRT. However, electrocardiographic imaging (ECGI) of ventricular electrical activation was at variance with this clinical effect (See figure). ECGI is a noninvasive modality for imaging epicardial potentials, electrograms, isochrones (activation sequences) and repolarization patterns from body surface electrocardiographic measurements2. Echocardiography in susbsequent months demonstrated progressive deterioration, with LV dilatation and diminishing ejection fraction. The patient deceased from heart failure shortly thereafter. Thus, this ECGI study had revealed lack of intended electrical effect of LV pacing, presaging CRT failure, despite symptomatic improvement. Non-invasive electrical imaging may have significant future utility for rapid assessment of pacing therapies.
Figure.
The figure depicts an ECGI-constructed epicardial isochrone map during simultaneous biventricular pacing (CRT). Epicardial surfaces of both ventricles are displayed in three views: anterior, left lateral, and posterior. There is overlap between adjacent views. The left anterior descending (LAD) coronary artery is marked. Selected ECGI-reconstructed epicardial electrograms are indicated by arrows. Pacing sites (RV and LV, asterisks), as expected, are the earliest ventricular sites to be activated (red). Thereafter, LV activation is irregular with development of regions of conduction block (thick black markings) and slowing (crowded isochrones) displaying fractionated local electrograms. These delay activation of a large territory of the lateral/posterolateral LV. In fact, this region is activated terminally (blue) despite pacing from an immediately adjacent site. Electrograms are preserved in this area indicating epicardial viability. Hence, LV pacing failed to achieve target area preexcitation.
Acknowledgments
In addition to the authors, Charulatha Ramanathan, PhD, Raja N. Ghanem PhD and Kyungmoo Ryu, PhD, also participated in the ECGI study.
The study was supported by NIH-NHLBI Merit Award R37-HL-033343 and Grant RO1- HL-49054 to Dr. Rudy.
Disclosures
Dr. Rudy chairs the scientific advisory board and holds equity in CardioInsight Technologies. He is an inventor of ECGI technology, for which Case Western Reserve University and Washington University hold patents.
Dr. Jia is an inventor of ECGI technology and is an equity holder and a paid employee of CardioInsight Technologies.
Dr. Varma is an investigator for CardioInsight Technologies.
References
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