The Curative Effect Of Cardiac Resynchronization Therapy By Targeted Left Ventricular Lead Placement Guided By Electrophysiological Mapping

Objectives: To investigate the curative effect of cardiac resynchronization therapy (CRT)by targeted left ventricular lead placement to the latest ventricular electrical activating sitemapped in the coronary sinus (CS) branches.Methods: Clinical data of25heart failure (HF) patients referred to Shenyang militarygeneral hospital for CRT therapy from February2011to February2013wereretrospectively analyzed. Twenty five patients with moderate to severe congestive heartfailure New York Heart Association (NYHA) functional class Ⅲ or Ⅳ，depressed LVejection fraction (LVEF)<0．35，and wide QRS complex≥120ms were included forimplantation of a CRT device．All patients signed informed consent. Patients with rightbundle branch block, postoperative time <12months were excluded. Patients were dividedinto research group and control group according to patient’s left ventricular lead (LVL)implantation approach. Left ventricular activating sequence was mapped in the CSbranches in research group，and the latest ventricular electrical activating site wasconsidered as the target site for LV lead placement．Patients in control group receivedconventional CRT treatment. Local electrical excitement delay compared with the onset of QRS was measured using pacemaker programmer after1year of CRT. The clinicalvariables assessed in this study included QRS duration, NYHA class,6-min walk test andechocardiography index. Echocardiography index included left ventricular ejectionfraction (LVEF), left ventricular end-systolic volume,(LVESV). The above parameterswere compared before and after CRT more than one year of follow-up.in each group andbetween two group.Results: The clinical baseline data showed no significant difference between researchgroup (11patients) and in the control group (14patients). CRTs were successfullyperformed in all patients with CRT-P pacemaker implantation in15patients and CRT-Dpacemaker implantation in10patients. All patients had no peri-operative complications.CS angiography showed an average of3.5±0.7CS branches were considered as apossible site for LV lead placement in each patient. LVL was successfully placed at thelatest LV electrical activating site in all11research group patients. Two patients inresearch group died （2/11，18%）during post CRT follow-up. One patient died of acutemyocardial infarction after two months of the CRT-D pacemaker implantation and suddendeath was occurred in the other patient after7months of CRT-P implantation. Anther9patients in research group had CRT response (9/11,82%) after post CRT one year followup, including3cases of CRT supper reaction (3/11,27%). The following clinical variables1year after CRT were markedly improved than variables before CRT in these9responders (all P<0．05)．NYHA class was improved (1.7±0.5vs3.2±0.4, p=0.06) and the6-min walk test was increased(488±26m vs286±67m，p=0.008)． Echocardiographydemonstrated LVEF was improved (48±10vs30±4, p=0.008)。left ventricular end systolicvolume was reduced (81±13ml vs149±43ml, p=0.008)．Four patients in control groupdied （4/14，29%）during post CRT follow-up. Two patients died of heart failure after2months and5months of the CRT-D pacemaker implantation, and sudden death wereoccurred in the other two patients after7months and1year of CRT-P implantation.Seven of14survived patients responded to CRT (7/14,50%) with1case of supper CRTreaction (1/14,7%).The following clinical variables1year after CRT were markedly improved than variablesbefore CRT in these10responders (all P<0．05)．NYHA class was improved (2.0±0.0vs 3.1±0.4, p=0.02) and the6-min walk test was increased (406±82m vs251±60m，p=0.005)． Echocardiography demonstrated LVEF was improved (37±6vs28±5,p=0.015)。left ventricular end systolic volume was reduced (89±10ml vs129±42ml,p=0.008). There were no statistically difference in response rate (82%vs50%, P=0.22),supper response rate (27%vs7%, P=0.42) and mortality (18%vs29%, P=0.89)between research group and control group during one year follow up. However, QRSwidth of research group is short than that of control group, LVEF and the six-minute walkdistance of research group improved significantly compared with the control group. Thepatients were divided into two groups according to local electrical excitement delay morethan90ms or less than90ms. LVEF, LESVE and QRS duration of patients in group oflocal electrical excitement delay more than90ms improved significantly compared withthe less local electrical excitement delay group.Conclusion: There were multiple CS branches could be considered as a possible site forLVL placement in CRT patient. Targeted left ventricular lead placement to the latestventricular electrical activating site guided by electrophysiological mapping in the CSbranches was feasible and with obvious curative effect during one year follow up. Themore local electrical excitement of LVL delayed, the better patient responded to CRT.