Prolonged asystole induced by head up tilt test. Report of four cases and brief review of the prognostic significance and medical management.

Abstract

Head up tilt is an established test for assessing patients with vasovagal syncope. Prolonged asystole during the test has previously been reported in patients suffering from the malignant form of this syndrome. Little is known about the prognostic significance of this response and there is no consensus about the optimum treatment. Four such patients are reported who were treated pharmacologically. During follow up they remained free from major events and their symptoms were welil controiled. Conservative management is the initial method of choice and only if this fails should implantation of a dual chamber permanent pacemaker be considered. (Heart 1997;77:273-275 A 72 year old woman presented with a five year history of recurrent syncope occurring about once a week. The episodes were preceded by lightheadedness and once resulted in head injury. Physical examination was normal. The ECG, echocardiogram, and x ray of the cervical spine were normal. A 48 hour tape showed asymptomatic episodes of bradycardia at 41 beats/min. She underwent a tilt test and at four minutes she developed abrupt syncope. The ECG showed asystole for 30 seconds, followed by complete atrioventricular block. She was returned to supine position and 0-6 mg of atropine was given, after which she recovered completely. Metoprolol, 25 mg three times a day, was prescribed and she remained asymptomatic for the following 15 months. CASE 4 A 20 year old woman gave a 10 year history of recurrent syncope occurring almost daily, preceded by nausea and vertigo and associated with occasional incontinence. Physical examination was normal apart from a soft systolic murmur. Her electrocardiogram showed nonspecific T changes; a 24 hour tape was normal and an echocardiogram showed mild mitral regurgitation. The tilt table test was positive, producing a 48 second asystolic pause at 40 minutes of head upright position, associated with incontinence. Cardiopulmonary resuscitation was started and the patient resumed sinus rhythm a few seconds later and regained consciousness. She was started on disopyramide, 250 mg twice a day, and after 13 months she still suffers infrequent presyncopal episodes but she has not had any further syncope. DiscussionThere is limited knowledge about the natural history of recurrent syncope although a documented non-cardiac cause as well as a normal 273 on 9 May 2018 by guest. Protected by copyright.

Tilt-induced asystole: a useful prognostic marker or clinically unrelevant finding?

“…In a few papers [16,30] a greater severity of symptoms (as assessed by the frequency of seizures or injury during spontaneous episodes) was observed before the initial evaluation in patients with tilt-induced asystole. However, in many other studies this finding was not confirmed and the clinical outcome of asystolic patients after tilt evaluation appeared to be not different from that of non-asystolic patients [27][28][29]31,32] . Indeed, the incidence of new syncopal events, in a pooled analysis, was 12% among 105 patients with tilt-induced asystole during a follow-up of 9 to 25 months (mean, 19) [ [16][17][18][27][28][29][30][31][32] compared to 35% among 218 control patients without asystole during a follow-up of 16 to 36 months (mean, 24) [28,29] .…”

“…Up to now only a few papers have examined the topic of a tilt-induced asystole [15][16][17][18][27][28][29][30][31][32] . On the whole, 714 patients with a positive response to head-up tilt testing have been studied.…”

“…The incidence was higher during nitrate provocation test (21%, 103 out of 489 patients) [5,6,10,[40][41][42][43]45] than during passive head-up tilt test (14%, 78 out of 568 patients) [25,[27][28][29][33][34][35]39] and isoproterenol test (13%, 34 out of 265 patients) [8,15,16,30,36,37,44] . The mean duration of asystole ranged from 7 to 30 s (mean, 14 s) [6,8,10,[15][16][17]25,[27][28][29][30][31][34][35][36]38,[40][41][42][43][44][45] . The longest reported pause was 73 s [18] .…”

“…Indeed, the incidence of new syncopal events, in a pooled analysis, was 12% among 105 patients with tilt-induced asystole during a follow-up of 9 to 25 months (mean, 19) [ [16][17][18][27][28][29][30][31][32] compared to 35% among 218 control patients without asystole during a follow-up of 16 to 36 months (mean, 24) [28,29] . Moreover, no case of important trauma, cardiopulmonary resuscitation or sudden death was observed in asystolic patients after initial evaluation [16][17][18][27][28][29][30][31][32] . As regards the correspondence between induced and clinical episodes of asystole, only limited information is available.…”

“…In particular, the implantation of a pacemaker based on the occurrence of a profound cardioinhibition during tilt testing, although repeatedly suggested [48][49][50][51] , appears not justified by currently available data. Indeed, electrical treatment with pacemaker in patients with tilt-induced asystole was not shown to be superior to drug or no therapy in preventing new syncopal episodes [15][16][17][27][28][29][30][31][32] . This is in contrast with the results of recently published prospective randomized trials that have apparently shown the value of pacemaker therapy in patients with vasovagal syncope and documented bradycardia/asystole during head-up tilt testing [49][50][51] .…”