Middle-term stability of epicardial left ventricular electrodes for cardiac resynchronization therapy

Abstract

IntroductionCardiac resynchronization therapy (CRT) is currently considered an effective and safe way to treat patients with severe heart failure. Unsuccessful attempts at endovascular insertion of the left ventricular (LV) electrode should prompt a consideration of having the electrode implanted by a cardiac surgeon. AimsThe aims of our work were to evaluate the electric parameters of CS-implanted LV electrodes and to compare them with transvenous implanted electrodes, identify the causes of endovascular implantation failure, compare the clinical and echocardiographic resynchronization effects, and compare the safety of both approaches. Methods and resultsPatients indicated for CRT had the LV electrode implanted either endovascularly (“endo” group) or epicardially (“epi” group; in cases of endovascular approach failure or as a part of another CS procedure). The trial was planned as a case–control study. Each group comprised 92 patients (26 females, 66 males) with an average age of 69 (epi) and 68 (endo) years, respectively. LV stimulation was effective at the 3-year follow-up in 98.1% of patients in the epi group and in 96.6% of patients in the endo group (p=NS). The groups were comparable with respect to the stimulation threshold both before discharge and at the 3-year follow-up. At the 1-month follow-up, this threshold was significantly higher in the epi group (1.62V vs. 1.06V, p<0.001) and the same was true for the 1-year and 2-year follow-ups (1.57V vs. 1.09V and 1.54V vs. 1.21V, respectively; p<0.001). Energetic output during LV stimulation was significantly higher in the epi group at all time points. The overall procedural effectiveness of endovascular implantation was 94.6%. Clinical response to CRT was noted in 71.4% of epi group patients and in 68.1% of endo group patients (p=NS). The average absolute increase in LV ejection fraction was comparable in both groups (6.0% vs. 7.2%, p=NS). Significantly higher 1- and 3-year mortality was noted in the epi group (19.0% vs. 5.5% and 21.7% vs. 6.5%, respectively; p<0.001). ConclusionEpicardial electrodes are capable of effective LV stimulation, as shown during middle-term follow-up. Epicardial LV stimulation is more demanding energetically. Resynchronization effects are similar in patients with epicardial and endocardial LV electrodes; however, the mortality of patients with epicardial LV electrodes seems to be significantly higher.