title: Clinical relevance of loss of atrial sensing in patients with single lead VDD pacemakers.
abstract: During single lead VDD pacing, loss of atrial sensing is reported to be 2%-11% of patients in the literature. The impact on quality-of-life and exercise duration has never been established. This study tried to assess the clinical relevance of loss of atrial sensing in patients with single lead VDD pacemakers. Twenty-one patients with total AV block were studied 3 months after single lead VDD pacemaker implantation. During a 6-minute walk test, atrial undersensing was verified and adjusted to achieve undersensing in < 5% (group 1), 5%-10% (group 2), and > 10% (group 3). Patients were allocated to each group in a randomized double blind crossover design. At the end of each 2-month study period all patients underwent symptom limited treadmill exercise testing. Subjective assessment of exercise difficulty was made using the Borg score, and quality-of-life assessment was performed using the Health Status Questionnaire. Exercise duration significantly decreased in group 3 (228 +/- 50 s) as compared to group 1 (257 +/- 42 s) and group 2 (250 +/- 46 sec) with an increase in the Borg score. Quality-of-life was decreased for three subscales in group 3 as compared to group 1 and group 2. In conclusion, atrial undersensing of > 10% in patients with single lead VDD pacing was associated with a decrease in exercise duration and increase in the subjective severity score, in addition to a decrease in quality-of-life. Atrial undersensing of < 10% did not effect exercise test results or quality-of-life. Since all studies reported intact atrioventricular synchrony in > or = 90% of patients, loss of atrial sensing is of limited clinical importance in these patients.
authors.affiliation: Academic Hospital VU, Dept. of Cardiology, P.O. Box 7057, 1007 MB Amsterdam, The Netherlands. cardiol@azvu.nl
authors.forename: C M
authors.initials: CM
authors.lastname: Van Campen
authors.forename: C C
authors.initials: CC
authors.lastname: De Cock
authors.forename: J
authors.initials: J
authors.lastname: Huijgens
authors.forename: C A
authors.initials: CA
authors.lastname: Visser
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001283:Atrioventricular Node / Q000503:physiopathology; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D018592:Cross-Over Studies; D015716:Electrocardiography, Ambulatory; D019544:Equipment Failure Analysis; D015444:Exercise / Q000502:physiology; D005260:Female; D006327:Heart Block / Q000503:physiopathology / Q000523:psychology / Q000628:therapy*; D006801:Humans; D008297:Male; D011788:Quality of Life; D011795:Surveys and Questionnaires; D013686:Telemetry