Left Ventricular Lead Position and Clinical Outcome in the Multicenter Automatic Defibrillator Implantation Trial–Cardiac Resynchronization Therapy (MADIT-CRT) Trial
How important is the position of the left ventricular (LV) lead in patients undergoing cardiac resynchronization therapy (CRT)?
This was a post-hoc analysis of 799 patients with cardiomyopathy, ejection fraction ≤30%, New York Heart Association class I-II heart failure (HF), and QRS ≥130 ms who received CRT in the MADIT-CRT trial. The position of the LV lead was documented by pre-implantation coronary venous angiography and post-implantation chest X-rays. The primary endpoint was death or HF.
In the short axis, the LV lead was positioned on the lateral wall in 59% of patients, the posterior wall in 22%, and the anterior wall in 19% of patients. There were no significant differences in HF or death between these lead positions. In the long axis, the LV lead was midventricular in 63%, basal in 23%, and apical in 14%. The prevalence of HF or death was significantly higher when the lead was apical (21.8%) than nonapical (13.3%).
The authors concluded that LV leads that are apical are associated with a higher risk of HF or death in patients with mild HF undergoing CRT.
In patients with a left bundle branch block, the LV apex often is activated earlier than basal regions. Placement of an LV lead for CRT in a region with the least amount of delayed activation is expected to be less clinically useful than when placed in basal regions of latest activation. This probably explains why the apical lead position was associated with worse outcomes in this study.
Keywords: Cardiomyopathies, Heart Failure, New York, Heart Ventricles, Defibrillators, Implantable, Cardiac Resynchronization Therapy
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