Multisite pacing as a supplemental treatment of congestive heart failure: the Medtronic Inc. InSync Study - INSYNC


Assessment of the saftey and efficacy of biventricular pacing in patients with refractory congestive heart failure.


Multisite ventricular pacing resynchronizes contraction of the failing left ventricle and improves cardiac performance.

Study Design

Study Design:

Patients Enrolled: 103
NYHA Class: 63% NYHA functional Class III and 37% Class IV
Mean Follow Up: 12 months
Mean Patient Age: 66 +/- 10 years
Mean Ejection Fraction: LVEF 21% +/- 9%

Patient Populations:

New York Heart Association Functinoal Class III or IV QRS Duration of >150 milliseconds LVEF <35% Left Ventricular End Diastolic Dimension >60 mm Absence of clinical improvement despite stable, standard medical therapy for 1 month


1. Prior pacing systems or indications or contraindications to pacing 2. Chronic atrial arrhythmias 3. Unstable angina, myocardial infarction or prior coronary artery revascularization or coronary angioplasty within the past 3 months 4. Existing implantable cardioverter defibrillator (ICD) or indications for an ICD

Drug/Procedures Used:

A multisite pacemaker (Medtronic InSync)was implanted with left ventricular pacing leads (Medtronic 2187 and 2188) implanted via a cardiac vein

Principal Findings:

7 of 10 patients during follow-up who exited the study had died. 4 of these were sudden deaths. There was a clinical benefit among surviving patients, which was corroborated by a significant improvement in NYHA functional class (improvement by 1.2) and in the Minnesota Living with Heart Failure Quality of Life Questionnaire Score (+40%) and by a longer distance covered during a 6-minute walk test (+25%). The clinical improvement was associated with a significant narrowing of the paced QRS complex during biventricular pacing, a significant decrease in the interventricular mechanical delay, and a trend towards an increase in the duration of ventricular filling.


This small study shows that multisite pacing is safe during a limited follow-up period and is associated with an improvement in exercise capacity. The results of this small, nonrandomized registry should be taken in the context of other small trials and larger randomized trials that support the efficacy of biventricular pacing in refractory congestive heart failure.


1. Gras D, Mabo P, Tang T, Luttikuis O, et al. Multisite pacing as a supplemental treatment of congestive heart failure: preliminary results of the Medtronic Inc. InSync Study. Pacing Clin Electrophysiol 1998 Nov;21(11 Pt 2):2249-55. 2. Leclercq C, Kass DA. Retiming the failing heart and clinical status of cardiac resynchronization. JACC 2002; 39:194-201.

Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Implantable Devices, Acute Heart Failure

Keywords: Follow-Up Studies, Cardiac Pacing, Artificial, Quality of Life, Heart Failure, Death, Sudden, Questionnaires, Cardiac Resynchronization Therapy

< Back to Listings