title: Functional behavior of patients with conventional pacemakers undergoing cardiac resynchronization.
abstract: BACKGROUND
  Cardiac resynchronization therapy (CRT) is an efficient treatment for patients with heart failure (HF), severe ventricular dysfunction and intraventricular block. Conventional pacemakers (CPM) implanted in the right ventricular apical area cause alterations in the normal sequence of cardiac activation similar to those induced by LBBB (left bundle-branch block). Therefore, patients with CPM and advanced HF could be candidates to undergo CRT, but as only small numbers of patients have been evaluated so far, definitive conclusions are lacking.
  
  
  OBJECTIVE
  To assess the clinical and functional outcome of cardiac resynchronization therapy (CRT) in patients with conventional pacemakers.
  
  
  METHODS
  Patients with CPM, who were in NYHA HF functional class III/IV class refractory to drug therapy, and left ventricular ejection fraction (LVEF) ) <35% underwent CRT. Patients clinical-functional behavior was assessed prospectively six months after the procedure. The improvement of one HF-functional class was set as an effective response to the procedure. The following was assessed: QRS duration (ECG), diastolic diameter (LVDd), left ventricular systolic diameter (LVSd) and LVEF seen on the echocardiogram. For the statistical analysis, Students paired t test and Spearmans correlation were used.
  
  
  RESULTS
  Twenty-nine patients (mean age 61.5) were evaluated. Of these, six were females, and chagasic cardiomyopathy was predominant. During the clinical follow-up of 22.7+/-13 months, 86.2% of the patients benefited from CRT. Within this group, the mean LVEF increased by 18% (p=0.013), QRS duration dropped by 11.8% (p=0.002) and no significant reduction in left ventricular intracavitary diameters was observed.
  
  
  CONCLUSIONS
  CRT is effective for patients with CPM and advanced HF as it yields a high rate of response (86.2%), significantly improves LVEF and reduces QRS duration.
authors.affiliation: Instituto do Coração (Heart Institute) do Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP - Brasil. rotasil@ig.com.br
authors.forename: Rodrigo Tavares
authors.initials: RT
authors.lastname: Silva
authors.forename: Martino
authors.initials: M
authors.lastname: Martinelli Filho
authors.forename: Carlos Eduardo Batista de
authors.initials: CE
authors.lastname: Lima
authors.forename: Daniela Garcia Moreno Cabral
authors.initials: DG
authors.lastname: Martins
authors.forename: Silvana Angelina Dorio
authors.initials: SA
authors.lastname: Nishióka
authors.forename: Anísio Alexandre
authors.initials: AA
authors.lastname: Pedrosa
authors.forename: Elizabeth Sartori
authors.initials: ES
authors.lastname: Crevelari
authors.forename: Roberto
authors.initials: R
authors.lastname: Costa
authors.forename: Eduardo Argentino
authors.initials: EA
authors.lastname: Sosa
authors.forename: José Antonio Franchini
authors.initials: JA
authors.lastname: Ramires
mesh_terms: D002037:Bundle-Branch Block / Q000628:therapy*; D002304:Cardiac Pacing, Artificial; D002598:Chagas Cardiomyopathy / Q000503:physiopathology / Q000628:therapy; D003971:Diastole / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000150:complications* / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012720:Severity of Illness Index; D013318:Stroke Volume / Q000502:physiology; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology