Efficacy of empirical cardiac pacing - Europe PMC

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To assess the results of this tactic we reviewed the records of. 104 patients who had received pacemakers for known or suspected bradycardia between Sep-.
I Original Research

Efficacy of empirical cardiac pacing in syncope of unknown cause Max F. Rattes, MD George J. Klein, MD, FRCPC, FACC Arjun D. Sharma, MD, FRCPC, FACC John A. Boone, MD, FRCPC Charles Kerr, MD, FRCPC Simon Milstein, MD

Cardiac pacing is often considered in patients with recurrent syncope after repeated attempts to document the cause have failed. To assess the results of this tactic we reviewed the records of 104 patients who had received pacemakers for known or suspected bradycardia between September 1973 and March 1985. The patients were classified retrospectively into three groups: group 1 (31 p4tients with a mean age of 73 years) had unequivocal documentation of bradycardia during syncope, group 2 (42 patients with a mean age of 71 years) had electrocardiographic or electrophysiologic evidence of potential bradycardia but no documentation during spontaneous syncope, and group 3 (31 patients with a mean age of 69 years) had a history "suggestive of' bradycardia-related syncope but no other evidence to support the diagnosis. The rates of recurrence of syncope during follow-up were 6.3%, 7.3% and 32.2% in groups 1, 2 and 3 respectively (p < 0.01). In group 3 recurrence was more probable in patients with loss of consciousness for more than 2 minutes than in those who were unconscious for 2 minutes or less (p < 0.05). The results suggest that pacemaker implantation is justified for recurrent syncope after extensive attempts to document a spell have failed if abnormal diagnostic test results suggest bradycardia as a possible cause. Empirical pacing is less satisfactory in patients with normal results of evaluation but may arguably be justified when patients have recurrent syncope with injury. From the departments of medicine, University of Western Ontario, London, and University of British Columbia, Vancouver

Reprint requests to: Dr. George J. Klein, University Hospital, PO Box 5339, Stn. A, London, Ont. N6A 5A5

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For prescribing information see page 469

Le malade qui presente des syncopes a repetition dont on n'a pu, en depit d'efforts soutenus, demontrer la cause est souvent muni d'un regulateur cardiaque. Afin de juger des resultats de cette maniere de faire on passe en revue les dossiers de 104 personnes a qui on a pose un regulateur de septembre 1973 a mars 1985 pour bradycardie connue ou supposee. On les classe retroactivement comme suit: groupe 1, 31 malades (Age moyen 73 ans) qui ont montre une nette bradycardie durant la syncope; groupe 2, 42 malades (age moyen 71 ans) qui ont des signes electrocardiographiques ou electrophysiologiques de bradycardie possible, sans demonstration de bradycardie durant une syncope spontanee; et groupe 3, 31 malades (Age moyen 69 ans) dont l'anamnese fait penser a une syncope par bradycardie, sans element objectif a l'appui. Le taux de recidive de syncope durant la catamnbse dans ces trois groupes est de 6,3%, 7,3% et 32,2% respectivement (p < 0,01). Dans le groupe 3 la probabilite d'une telle rdcidive est plus forte chez les sujets dont la perte de connaissance avait durd plus de 2 minutes (p < 0,05). Le tout donne a penser que la pose d'un rdgulateur est indiquee dans le cas de syncopes a repdtition lorsque la bradycardie, meme non dEmontrd durant une attaque, est rendue probable par l'existence d'anomalies lors d'examens diagnostiques. Lk ou celles-ci n'existent pas, la pose empirique d'un rdgulateur est moins fructueuse. On pourrait cependant arguer en sa faveur chez le malade dont les syncopes ambnent des blessures.

P) atients who present with recurrent syncope frequently undergo extensive evaluation to determine its cause. It has been estimated that the cause of syncope remains unknown even CMAJ, VOL. 140, FEBRUARY 15, 1989

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after extensive diagnostic evaluation in 13 % to 48% of patients.1-3 In clinical practice permanent cardiac pacing may be considered, although the efficacy of empirical permanent pacing in this setting has not been determined. We reviewed the records of patients who had received pacemakers for known or suspected bradycardia to assess the efficacy of empirical pacing and to determine clinical variables that would predict the success of pacing in preventing recurrence of syncope. Methods Patients and data collection We reviewed the records of 197 patients admitted to the participating centres between September 1973 and March 1985 for evaluation of known or suspected bradycardia-related syncope. The records reviewed were from our personal clinical files (at St. Paul's Hospital, Vancouver, and Vancouver General Hospital) and the files of the Pacemaker and Arrhythmia clinics at University Hospital, London, Ont. Syncope was defined as transient loss of consciousness characterized by unresponsiveness and loss of postural tone with spontaneous recovery, not requiring specific resuscitative interventions.4 Eighty patients were excluded because of evidence of non-bradycardia-related syncope or insufficient clinical data for analysis. In addition, 13 patients who had received pacemakers for syncope had died (in 8 cases) or had been lost to follow-up by the pacemaker clinic (in 5). The mean age of the patients who had died was 72 years, and they had been followed for a mean of 29 months. Six of the eight had had organic heart disease. The cause of death was carcinoma in two patients, acute myocardial infarction in one and unknown in the remainder. Four of the eight Table I

deaths would have been in group 3, three in group 2 and one in group 1. The remaining 104 patients (56 men and 48 women), who had received a permanent pacemaker, were interviewed, with witnesses when available, during routine pacemaker follow-up or by telephone. Information obtained included patient's age and sex, time from the first syncopal episode to implantation, total number of syncopal episodes and number of syncopal episodes 1 year before pacemaker implantation, presence or absence of prodromal or postsyncopal symptoms and duration of loss of consciousness (2 minutes or less, or more than 2 minutes, by the best estimate of the patient or witness). Syncope was also characterized as to the presence or absence of a precipitating factor, seizure activity, occurrence of physical injury and availability of a reliable witness. The presence of organic heart disease and a family history of sudden death were also noted. Other information recorded included number of drugs used before pacemaker implantation, response to carotid sinus massage, orthostatic drop in blood pressure and investigations done before pacemaker implantation. Investigations done before pacemaker implantation varied with individual clinicians. Routine blood studies, including determination of levels of electrolytes, creatinine and random serum glucose and a complete blood count, had been done in all patients. Other laboratory studies had included routine 12-lead electrocardiQgraphy, chest roentgenography, in-hospital telemetry or at least one 24-hour period of Holter monitoring, treadmill exercise testing, M-mode or 2-D echocardiography or both, a cardiac wall motion study, heart catheterization, electroencephalography, computed tomography (CT) and an electrophysiologic study (Table I). Most of the investigations had been done in patients without documentation of bradycardia

Diagnostic investigations done in 104 patients admitted to hospital for known or suspecteG

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bradycardia-related syncope I.

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