Comparison of Left Ventricular–Biventricular Pacing on Ventricular Synchrony, Mitral Regurgitation, and Global Left Ventricular Function in Patients With Severe Chronic Heart Failure Dragos Vinereanu, MD, Rob Bleasdale, MD, Mark Turner, MD, Michael P. Frenneaux, MD, and Alan G. Fraser, MD We compared the effects of left ventricular and biven- tricular pacing in 16 patients (15 men and 1 woman; aged 64  8 years) with severe heart failure by conventional and tissue Doppler echocardiography. Intraventricular synchrony, regional and global sys- tolic function, diastolic function and filling time, and the severity of secondary mitral regurgitation were similar between left ventricular and biventricular pacing. 2004 by Excerpta Medica, Inc. (Am J Cardiol 2004;94:519 –521) C ardiac resynchronization therapy has been shown to reduce mortality from progressive heart failure in patients with severe left ventricular (LV) dysfunc- tion. 1 It also improves exercise capacity, symptoms, and quality of life. The mechanisms responsible for these benefits are improved synchrony of the left and right ventricle (interventricular synchrony), 2,3 im- proved synchrony of the different segments of the left ventricle (intraventricular synchrony), 4 and decreased secondary mitral regurgitation. 5 LV pacing alone has exhibited comparable improvements to biventricular (BiV) pacing during acute hemodynamic or echocar- diographic evaluation. 6–8 However, no detailed com- parative data on the acute effects of LV versus BiV pacing on intra- and interventricular synchrony are available. We set up a crossover study to compare the effects of LV and BiV pacing on ventricular syn- chrony, mitral regurgitation, and global systolic and diastolic function using conventional and tissue Dopp- ler echocardiography. ••• Sixteen consecutive patients (aged 64  8 years; 15 men and 1 woman) with a BiV InSync III pace- maker (Medtronic Inc, Minneapolis, Minnesota) were studied between 1 and 6 months after transvenous implantation, with a lead placed via the coronary sinus over the free wall of the left ventricle. Right-sided cardiac leads were conventionally placed in the right atrial appendage and the right ventricular apex. All patients were in sinus rhythm when unpaced, and patients with aortic or mitral valve stenosis, peri- cardial disease, or cor pulmonale were excluded. Be- fore pacing, the duration of the QRS complex was 135  31 ms. Three patients (19%) were in New York Heart Association functional class II, 12 patients (75%) were in class III, and 1 patient (6%) was in class IV. Etiology of heart failure was ischemic in 11 patients (70%) and nonischemic in 5 (30%). Fifteen patients were taking an angiotensin-converting en- zyme inhibitor, 2 were on a  blocker, and all were taking a loop diuretic. The protocol was approved by the local research ethics committee, and each patient gave written informed consent. The paced atrioventricular delay was optimized by conventional Doppler assessment of transmitral flow. 9 The pacemaker was switched off, and after 10 minutes of rest, a detailed transthoracic echocardiographic study was performed. The pacemaker was then repro- grammed to atrio-LV mode, and the echocardio- graphic study was repeated after another 10-minute period of stabilization. Finally, the pacemaker was reprogrammed to BiV mode with simultaneous VV stimulation, and echocardiography was performed again after a further 10-minute period of stabilization. This sequence was used for all patients. Heart rate was measured during each stage. The electrocardiogram was recorded simultaneously. Patients were studied in the left lateral decubitus position using a commercially available ultrasound system equipped with tissue Doppler (Vingmed Sys- tem 5, GE Vingmed, Horten, Norway), using a 1.5- to 2.5-MHz transducer. Digital echocardiographic data were acquired during passively held end-expiration. Standard echocardiographic studies consisted of M-mode, cross-sectional, and Doppler blood flow measurements. LV ejection fraction was calculated by the modified biplane Simpson’s method. The rate of increase in LV pressure in systole was estimated from the continuous-wave Doppler trace of the mitral re- gurgitant jet, between velocities of 1 and 3 m/s. 10 Global diastolic function was assessed from color M-mode recordings of mitral inflow, and flow propa- gation velocity was measured. 11 Filling time was mea- sured from pulse-wave Doppler recording of the trans- mitral flow. The severity of secondary mitral regurgitation was estimated in the apical 4-chamber view by measuring the width of the vena contracta 12 and by calculating the regurgitant orifice area using the proximal isovelocity surface–area method. 13 Tissue Doppler echocardiography used 5 standard imaging planes: parasternal long-axis, parasternal short-axis, apical 4-chamber, apical 2-chamber, and apical long-axis views. Myocardial velocities and tim- From the Wales Heart Research Institute, Cardiff, United Kingdom. Dr. Fraser’s address is: Wales Heart Research Institute, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, United Kingdom. E-mail: fraserag@cf.ac.uk. Manuscript received February 2, 2004; revised manuscript received and accepted April 22, 2004. 519 ©2004 by Excerpta Medica, Inc. All rights reserved. 0002-9149/04/$–see front matter The American Journal of Cardiology Vol. 94 August 15, 2004 doi:10.1016/j.amjcard.2004.04.072