NEW YORK (Reuters Health) – When unfavorable anatomy of the cardiac veins impedes transvenous placement of left ventricular leads for cardiac resynchronization therapy (CRT), implantation via a minithoracotomy is preferable, according to an Italian group.
The improvement seen in their study “suggests that physicians should consider the epicardial implantation as the first line approach in patients with unfavorable CS (coronary sinus) anatomy,” the authors write in the July 26 issue of the Journal of the American College of Cardiology.
Dr. Piergiuseppe Agostoni at the Centro Cardiologico Monzino, Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS) in Milan, and colleagues note that correct engagement of the left ventricular (LV) lead in the area of highest intraventricular impedance via transvenous placement is achieved in only about 70% of patients undergoing a CRT procedure.
“Failing to position the LV catheter over the target area is considered the main cause of inefficacy of CRT,” they explain. “In patients with unfavorable anatomy of CS main branches, the surgical direct minithoracotomic intervention may represent an alternative, viable strategy to implant the LV catheter over the posterolateral wall of the LV.”
To compare these two approaches, the researchers used multislice computed tomography (MSCT) to identify unfavorable anatomy of CS main veins in 40 heart failure patients with indications for CRT. Half the patients were assigned to LV lead implantation through a conventional transvenous endocardial approach while the other 20 had LV lead implantation by epicardial minimally invasive thoracotomy with video-assisted thoracoscopy.
In the latter group, the leads were placed over the middle-basal segments of the posterolateral wall of the left ventricle, whereas this was not possible in the transvenous group, according to the report.
At 1-year follow-up, LV ejection fraction improved from 28.8% to 33.9% in the surgical group but remained at 27.4% in the transvenous group. On exercise testing, peak oxygen uptake improved from 10.4 to 13.1 mL/kg/min and from 11.2 to 11.3 mL/kg/min in the two groups, respectively, the investigators found.
Between-group differences in post-CRT changes were highly significant, Dr. Agostoni and colleagues report.
They comment, “Data from this study underline the importance of the pre-operative knowledge, gained in the present study by MSCT, of CS main branches anatomy, because it allows the screening of patients with unfavorable anatomic patterns.”
The conclude, “In these patients, an accurate electrophysiologically and hemodynamically guided LV lead positioning over the posterolateral wall of the LV by the minithoracotomic surgical approach is preferable.’
However, an editorial raises the question of radiation exposure with such an approach. “Fluoroscopy times during CRT implants can be prolonged and the long-term risks of performing a CT scan in addition are unknown,” write Drs. Kenneth Ellenbogen and Jordana Kron, with the Virginia Commonwealth University Medical Center in Richmond.
“While we await the results of future trials, we do not feel a change in clinical practice is warranted based on the current state of knowledge, and we do not endorse preprocedural CT scans because of concern about increased radiation exposure,” they advise.
J Am Coll Cardiol 2011;58:483-492.