Safety and the Effects of Isolated Left Ventricular Pacing in Patients With Bradyarrhythmias

Over the past several years, there has been growing concern over the significant deleterious effects of RV pacing, including electromechanical dyssynchrony, proarrhythmia and development of heart failure (HF). However, it remains unclear whether pacing-related ventricular dyssynchrony can translate into significant LV structural changes and produce important clinical impairment in an average pacemaker population with compromised AV conduction. Alternatively, left ventricular pacing has been shown to minimize ventricular dyssynchrony and to improve symptoms and prognosis in patients with mild to moderated systolic HF and prolonged QRS duration.

This randomized controlled study is been conducted to compare the effects of conventional right ventricular (RV) pacing vs. left ventricular (LV) in patients with AV block. The hypothesis is that isolated LV pacing through the coronary sinus can be used safely and provide greater hemodynamic benefits to patients with AV block and normal ventricular function who require only the correction of heart rate.

Specifically, the investigator aims are to evaluate the safety, efficacy and the effects of left ventricular pacing using active-fixation coronary sinus lead-the Attain StarFix® Model 4195 OTW Lead, compared to right ventricular pacing in patients with implantation criteria for conventional pacemaker stimulation.

• Left ventricular pacing through coronary sinus tributaries (Attain StarFix) (Device), also known as Attain StarFix® Model 4195 OTW Lead: Left ventricular pacing in patients with bradycardia
• Right ventricular pacing (Medtronic) (Device), also known as Right ventricular lead Medtronic 5076-58: Conventional right ventricular pacing in patients with bradycardia.

Primary outcomes

• Surgical success [Participants will be evaluated during the perioperative period and during the hospital stay, an expected average of 2 days]: Surgical success: absence of complications

Secondary outcomes

• Echocardiographic and Clinical composite [Participants will be evaluated at 6 and 24 months after PM implantation]: Echocardiographic: ventricular dysfunction Clinical composite: all mortality, cardiovascular mortality, hospitalization, heart failure

Other outcomes

• Quality of Life [Participants will be evaluated at 6 and 24 months after PM implantation]: Quality of life: improvement on quality of life scores measured by three questionnaires: 36-Item Short Form Health Survey (SF-36), a disease specific questionnaire for pacemaker patients (Aquarel) and Minnesota Living With Heart Failure (MLWHF).

Sex: All, ages: 18 Years to 90 Years

Inclusion Criteria:

* Older than 18 years
* Pacemaker initial implant by transvenous approach
* Presence of AV block
* Presence of atrial fibrillation / atrial flutter with slow ventricular response
* Left ventricular systolic function > 0.40
* Subject agreed to participate and signed the consent form

Exclusion Criteria:

* Absence of venous access
* Impediment of venous access due to presence of intracardiac defects
* Impediment of venous access due to presence of tricuspid valve prosthesis
* Need for radiotherapy in the chest
* Presence of chest deformity
* Pregnancy
* Life expectancy of less than one year
* Contraindication to administration of iodinated contrast (creatinine > 3.0) Unable to attend the follow-up appointments

• Roberto Costa, MD PhD, Principal investigator, University of Sao Paulo