The STOP VT study, as reported in the 14th issue of Cardiac Rhythm News, showed that remote magnetic navigation may provide additional benefits to catheter ablation for the treatment of scar-related ventricular tachycardia. Rainer Moosdorf, Department of Cardiovascular Surgery, Philipps – University Marburg Medical School, Germany, reviews the impact of this study.
By Rainer Moosdorf
The STOP VT study is remarkable in two aspects. The first one is that, with the new magnetic steering technology, ablation of scar related ventricular tachycardia has become more reliable and more successful and the investigators of the study have to be congratulated for their good results. These results should-and this is the second aspect-remind us, that ventricular tachycardia do nearly always have a pathological substrate at the border between scar and vital myocardium, which may be addressed by different ablation techniques as a curative therapy in contrast to the implantable cardioverter device (ICD), which is highly effective in terminating ventricular arrhythmias but is not treating the disease.
There are numerous patients with VTs who will benefit from curative attempts not only in terms of cardiac mortality but also in terms of quality of life. This makes a significant difference to the ICD. The new ablation technologies described will widen the field of interventional options and surgical options, and should be considered in any patients with documented VTs and an indication for cardiac surgery.
A working group at University Marburg Medical School, including myself, and Robert Svenson, cardiologist and electrophysiologists, Carolinas Heart Center in Charlotte, North Carolina, before retiring, have developed a mapping guided laser ablation technique, which may be applied endo- and epicardially without significantly increasing the procedural time or increasing the risk of complications during cardiac operations. Importantly we have learned from clinical studies that besides the well known subendocardial re-entry circuits, there are also subepicardial circuits that should be mapped and ablated to avoid recurrences. This is still a weak point of all catheter based techniques, which are limited to a sole endocardial ablation.
The endo- and epicardial approach is applied in the presence of major scar or aneurysms and has a cure rate of more than 90% (freedom from any inducible VT) (Moosdorf R, et al. American Heart Journal 1994; 127: 1133–38) and even the sole epicardial ablation, which may avoid a ventriculostomy in the absence of major scar, has a cure rate of around 60% (D Pfeiffer, et al. Circulation 1996; 94:3221–25). This means that with the combined approach, the vast majority of patients may be left without an ICD and will not experience any shocks.
Even the limited epicardial ablation provides a success rate of more than half. Additionally, many of the remaining patients, who received an ICD, did not experience a clinical ventricular tachycardia with the necessity of a shock. It may be expected that curative techniques, may they be interventional or surgical, will attract more interest again in the treatment of patients with ventricular tachycardia.