Table 1 Studies completed or well advanced

VIGOR CHF [22]

Thoracotomy

Severe CHF due to DCM sinus rhythm intraventricular conduction delay

Randomised single-blind active versus no pacing for 6 weeks then VDD for a further 12 weeks

VO₂ max

6 min walk distance Quality of life questionnaire Plasma norepinephrine

Study will be reported shortly

VENTAK

Echocardiographic assessment

Completion Spring 2001

PATH CHF [40]

Thoracotomy

NYHA III/IV CHF Sinus rhythm > 55/min QRS > 120 ms PR > 150 ms; 42 patients

(1) Acute phase: acute haemodynamic study at time of implant to evaluate optimal pacing site and AV delay

Haemodynamics

-

(1) LV pacing superior to biventricular; both superior to RV pacing; optimisation of AV delay important

(2) Chronic phase: single-blind, cross-over study biventricular pacing versus best unventricular pacing site assessed in acute study

VO₂ max 6 min walk distance

Quality of life questionnaire Echocardiographic assessment

InSYNC

Transvenous

NYHA III / IV (48% IHD) EF < 35% LVEDD > 60 mm QRS > 150 ms 103 patients on optimal therapy

Non-randomised trial Patients were implanted with biventricular pacer and assessed at 1, 3, 6 and 12 months

6 min walk distance QRS duration

NYHA class Quality of life

Completed Improvement in QOL, 6 min walk, reduction in QRS, symptoms irrespective of aetiology

MUSTIC [35]

Transvenous

NYHA III, EF < 35% QRS ≥ 150 or 180 for AF group Group I: sinus rhythm Group II: AF with AV node ablation

Single-blind, randomised, cross-over 12 weeks of biventricular versus no ventricular stimulation followed by a longitudinal phase in the patients preferred mode

6 min walk distance VO₂ max

Mortality or need for transplant/LVAD QOL Rehospitalisation and/or changes in drug therapy for decompensated CHF

Results in sinus rhythm group → improved 6 min walk distance, VO₂ max and QOL AF data to be presented late 2000