Optimal Pacing for Symptomatic AV Block: A Comparison of VDD and DDD Pacing MAX HUANG, ANDREW D. KRAHN, RAYMOND YEE, GEORGE J. KLEIN, and ALLAN C. SKANES From the Division of Cardiology, University of Western Ontario, London Ontario Canada HUANG, M., ET AL.: Optimal Pacing for Symptomatic AV Block: A Comparison of VDD and DDD Pacing. VDD pacing provides the physiological benefits of atrioventricular synchronous pacing with the conve- nience of a single lead system, but is hampered by uncertainty regarding long-term atrial sensing and potential development of sinus node disease. To examine the long-term reliability and complication rates of VDD pacing, we compared the outcome of 112 consecutive patients (age 70 ± 13 years, 59% male) with symptomatic AV block who received a single pass bipolar VDD system to 80 patients (age 63 ± 16 years, 70% male) who received DDD pacing for the same indication. All patients were judged to have intact sinus node function based on submitted ECGs and monitoring results at the time of implant. Implant time was reduced in VDD patients compared to DDD patients (63 ± 20 vs 97 ± 36 minutes, P < 0.0001). Implant complications occurred in 5 (6%) DDD patients compared to 3 (3%) VDD patients (P = 0.15). The implant P wave was lower with VDD pacing compared to DDD patients (2.91 ± 1.48 vs 4.0 ± 1.7 mV, P < 0.0001), but remained stable during long-term follow-up in both groups. During 17.7 ± 10.0 months of follow-up in the VDD group, only 2 VDD patients were reprogrammed to VVIR mode, compared to 3 DDD patients. Physiological atrioventricular activation was maintained in 94%–99% of beats throughout the follow-up period in the VDD group. VDD pacing is an excellent strategy for treatment of patients with symptomatic AV block. The lower cost, high reliability, and abbreviated implantation time suggest that VDD pacing is a viable alternative to DDD pacing in patients with high-degree AV block and normal sinus node function. (PACE 2003; 26:2230–2234) pacemaker, AV block, treatment Introduction Most clinicians consider use of dual cham- ber pacing for symptomatic AV block in order to maintain AV synchrony. 1-4 VDD pacing utiliz- ing a single pass lead with far-field atrial sens- ing bipoles is a potentially simpler approach to provide the physiological benefits of atrioven- tricular synchronous pacing block with a single lead system. Despite this, VDD pacing is utilized in only 1% of patients receiving pacemakers in North America, though it is more widely used in Europe. 5-12 This may be related to concern regard- ing stability of atrial sensing, or development of sinus node disease. Nonetheless, a single lead sys- tem has the potential to reduce procedure time and complications, and reduce pacing system cost compared to dual chamber pacing. We compared the implant and outcome of patients with symp- tomatic AV block managed with VDD versus DDD Supported by a grant from the Heart and Stroke Foundation of Ontario (NA3397). Dr. Krahn is a Research Scholar of the Heart and Stroke Foundation of Canada. Address for reprints: Andrew Krahn, M., London Health Sci- ences Center, University Campus, 339 Windermere Road, London Ontario Canada, N6A 5A5. Fax: (519) 663-3076; e-mail: akrahn@uwo.ca Received September 13, 2002; revised May 6, 2003; accepted June 13, 2003. pacing systems to assess the long-term stability and viability of VDD pacing. Methods Patients One hundred twelve consecutive patients with second- or third-degree atrioventricular blo- ck, normal sinus function, and VDD pacemak- ers were included in this retrospective study. Pa- tients were implanted between January 1, 1998 and October 1, 2000 to allow a minimum of one year of follow-up after implant. To provide a com- parison population, 89 consecutive DDD patients with second- or third-degree atrioventricular block with normal sinus function were also included in this study. These patients were implanted between January 1, 1996 and October 1, 2000. Patients were included in the study if they un- derwent first time pacemaker insertion, had symp- tomatic second- or third-degree AV block, normal sinus function as judged by in patient monitoring or out patient referral material, and a minimum of one year of follow-up. Sinus node function was judged based on resting heart rate and submitted clinical data, and did not involve prospectively de- fined monitoring parameters. Wenkebach second- degree AV block was considered significant if it oc- curred at heart rates ≤ 120 beats/min during sinus rhythm or atrial pacing. Patients were excluded if 2230 December 2003 PACE, Vol. 26