A STUDY COMPARING VVI AND DDI PACING IN ELDERLY PATIENTS WITH CAROTID-SINUS SYNDROME

Objective-To determine whether single chamber ventricular demand (WI) pacing is adequate for elderly patients with carotid sinus syndrome. D esign-Prospective double blind randomised cross over study. Setting-Te rtiary referral centre Patients-30 consecutive patients aged over 60 y ears with carotid sinus syndrome referred for cardiac pacing. Interven tion-Patients underwent chamber pacemaker implantation were then rando mised to two three-month periods of VVI and DDI pacing. Main outcome m easures-Responses to cardiovascular tests (vasodepression during carot id sinus massage, pacemaker effect, postural blood pressure measuremen ts, and response to head up tilt), and symptoms. Results-11 patients d eveloped profound hypotension during upright carotid sinus massage whi le pacing WI compared with only two while pacing DDI. The upright pace maker effect was greater in WI (WI, -31 (SD 19) mm Hg v DDI, -4 (12) m m Hg; P < 0.001). Postural blood pressure measurements and responses t o head up tilt did not vary. Eleven patients were unable to tolerate W I pacing and had to be withdrawn early from this limb of the study (gr oup A). Fourteen of the remainder completed diary cards and did not ex press a preference (group B). No patient preferred WI. Group A patient s were older (group A, 78 (6) years v group B, 70 (9) years; P < 0.05) , were more likely to be female (group A, 73% v group B, 14%; P < 0.01 ), and were more likely to have orthostatic hypotension while pacing D DI (group A, 46% v group B, 0%; P < 0.01). Group A and B patients coul d not be differentiated by other prepacing clinical or haemodynamic va riables. Conclusions-Elderly patients with carotid sinus syndrome are likely to develop symptomatic hypotension following WI pacing. The opt imum pacing mode for individual patients cannot be predicted by simple cardiovascular tests before pacing.