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.