Minimizing right ventricular pacing in patients with sinus node disease and prolonged PQ interval: The impact on exercise capacity.
BACKGROUND
Several clinical and experimental studies have shown that unnecessary right ventricular pacing in sinus node disease can be detrimental. Inter- and intra-ventricular asynchrony imposed by right ventricular pacing may cause reduction in contractility and relaxation of left ventricle, worsening mitral regurgitation, regional redistribution of myocardial perfusion and oxygen consumption, and asymmetrical hypertrophy of left ventricular wall. In some patients, sinus node disease coexists with impaired atrioventricular conduction. The optimal pacing mode in this population is not determined. Minimizing right ventricular pacing can preserve inter- and intra-ventricular synchrony. On the other hand, longer atrioventricular delay may cause atrioventricular asynchrony. The aim of this study was to prospectively assess the impact of minimizing right ventricular pacing in patients with DDD pacemaker implanted for sinus node disease and prolonged PQ interval on exercise capacity, cardiac function and quality of life.


METHODS
The study enrolled 50 consecutive patients with prolonged PQ interval who were implanted with DDD pacemaker because of sinus node disease. Each patient was treated alternately with 2 pacing modes in random order for 4-month periods: conventional dualchamber pacing and dual-chamber minimal ventricular pacing (prolonged atrioventricular delay). At the end of each phase the following tests were performed: cardiopulmonary exercise testing, echocardiographic evaluation and quality of life assessment (SF36).


RESULTS
There was no significant relationship between pacing mode and cardiopulmonary parameters, echocardiographic parameters and quality of life.


CONCLUSIONS
Sequential atrioventricular pacing may be a reasonable choice for treating patients with sinus node disease and prolonged PQ interval.
Department of Cardiology and Internal Diseases, Military Institute of Medicine, Warsaw, Poland. krystian.krzyzanowski@gmail.com.
Krystian
K
Krzyżanowski
Dariusz
D
Michałkiewicz
Zbigniew
Z
Orski
Robert
R
Wierzbowski
Robert
R
Ryczek
Andrzej
A
Cwetsch
D000200:Action Potentials; D000368:Aged; D000369:Aged, 80 and over; D054537:Atrioventricular Block / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000379:methods; D018592:Cross-Over Studies; D004452:Echocardiography; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial; D011044:Poland; D011446:Prospective Studies; D011788:Quality of Life; D020127:Recovery of Function; D012804:Sick Sinus Syndrome / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D011795:Surveys and Questionnaires; D013997:Time Factors; D016896:Treatment Outcome; D016278:Ventricular Function, Right