- In patients with mild heart failure and left bundle branch block who received a cardiac resynchronization therapy defibrillator (CRT-D), posterior or lateral left ventricular (LV) lead location was associated with significant long-term mortality reduction, accompanied by LV reverse remodeling
- CRT-D patients with anterior and posterior/lateral LV lead locations had a significant reduction in heart failure events during long-term follow-up
- An apical LV lead location should be avoided
In 2009, the international MADIT-CRT trial showed that in patients with mild heart failure, placement of an implantable cardioverter-defibrillator (ICD) with cardiac resynchronization therapy (CRT) reduced the rate of death or heart failure–related clinical events compared with ICD alone. Mild heart failure was defined in MADIT-CRT as left ventricular (LV) ejection fraction <30% and a QRS duration >130 ms. The benefit was great enough that the trial was stopped early.
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Later analysis of the MADIT-CRT data showed that in the subgroup treated with both CRT and ICD (CRT-D), an LV apical lead position was associated with poorer clinical outcomes. However, the long-term effects on clinical outcomes were unknown.
A new post hoc analysis of the MADIT-CRT data has demonstrated that the LV lead location and QRS morphology impacts long-term outcomes. Jagmeet P. Singh, MD, ScM, DPhil, associate chief of Cardiology, and colleagues published their findings in JACC: Clinical Electrophysiology.
A total of 110 hospitals participated in MADIT-CRT. After the trial was stopped, the Food and Drug Administration required long-term follow-up for U.S. patients, which was accomplished at 48 of 88 centers. Altogether, 854 patients were followed for a median of 5.6 years.
The current study evaluated 569 patients who had been implanted with a CRT-D and had left bundle branch block (LBBB) at baseline as part of the MADIT-CRT trial follow-up. They were compared with a control group of 505 patients with LBBB who had been in the ICD arm of the trial.
Altogether, 83 of the CRT-D patients had apical leads. Of the other 486 patients, 99 had anterior leads and 387 had posterior or lateral leads, which were combined because outcomes proved to be similar in those two groups.
The principal findings were:
- Among patients with LBBB and posterior/lateral LV leads, CRT-D was associated with a 46% reduction in all-cause mortality and a 56% reduction in heart failure events, compared with ICD only. CRT-D was also associated with better LV reverse remodeling
- Among patients with LBBB and an anterior LV lead location, CRT-D was associated with a 50% reduction in heart failure events, compared with ICD only. There was no reduction in mortality with CRT-D
- CRT-D was not associated with improved outcomes in non-LBBB patients, regardless of LV lead location
The researchers conclude that when patients with mild heart failure and LBBB are candidates for a CRT-D, posterior or lateral LV lead positioning should be considered whenever possible. Quadripolar leads are preferable in most cases, they say, to achieve a basal or mid-ventricular pacing site. An apical LV lead location should be avoided.
Recommendations are unclear for CRT-D candidates who do not have LBBB, the authors add. In these patients, LV electrical activation and therefore optimal LV lead location are more heterogeneous.
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