High-amplitude left ventricular pacing in cardiac resynchronization therapy: an alternative way to increase response rate in non-responders

Purpose

This study compared patients who underwent cardiac resynchronization therapy (CRT) by high-amplitude left ventricular (LV) pacing with those who underwent CRT by standard LV pacing.

Methods

We included 32 CRT patients with ejection fraction (EF) ≤35%, QRS time ≥120 ms, and New York Heart Association (NYHA) class III/IV symptoms of heart failure despite optimal medical treatment. These patients were evaluated clinically and echocardiographically before, three and six months after CRT. At the 3^rd month, the LV pulse amplitude value was set high at 5 volt for 16 patients [high-amplitude Group (HAG)], while for the other 16 patients, it was reduced to at least twice the threshold value at ≤2.5 volt [low-amplitude group (LAG)].

Results

Clinical and echocardiographic response rates of HAG and LAG after CRT were similar in the 3^rd and 6^th month. In both groups, increase in LVEF and decrease in LV ESV in the 3^rd and 6^th month were statistically significant compared to those before CRT, and NYHA class and end-diastolic volume (EDV) was significantly reduced in the 6^th month compared to those before CRT. However, NHYA class and EDV continued to reduce significantly in HAG from the 3^rd to the 6^th month (P<0.05), while the decrease in LAG was not significant (P>0.05). The rate of mitral regurgitation (MR) was reduced significantly in HAG in the 6^th month compared to that before CRT, while the decrease in LAG was not significant (P<0.05; P>0.05 respectively).

Conclusions

CRT by high-amplitude LV pacing was more effective according to clinical and echocardiographic evaluations. It should be considered as an alternative in non-responsive patients.KEYWORDS : Heart failure (HF), cardiac resynchronization therapy (CRT), echocardiography, high-amplitude left ventricular pacing