North American Vasovagal Pacemaker Study: study design and organization

The relationship between health-related quality of life and frequency of spells in patients with syncope

Chronic syncope has a wide range of symptom burden, and anecdotal data suggest substantial but variable physical and psychosocial morbidity. We hypothesized that health-related quality of life (HRQL) is impaired in syncope patients and the degree of impairment is proportional to syncope frequency. The EuroQol EQ-5D was completed by 136 patients (79 female and 57 male) with mean age 40 (SD = 17) prior to assessment. HRQL was substantially impaired in syncope patients compared to population norms in all five dimensions of health measured by the EQ-5D. In patients with six or more lifetime syncopal spells there was a significant (P < 0.001) negative relationship between the frequency of spells and overall perception of health, which was not evident in those who had a history of less than six lifetime spells. These relationships were maintained after controlling for comorbid conditions.

Cardiac pacing for severe childhood neurally mediated syncope with reflex anoxic seizures

OBJECTIVE

To determine whether permanent cardiac pacing could prevent syncope and seizures in children with frequent severe neurally mediated syncope, and if so whether dual chamber pacing was superior to single chamber ventricular pacing.

METHODS

Dual chamber pacemakers were implanted into 12 children (eight male, four female) aged 2-14 years (median 2.8 years) with frequent episodes of reflex anoxic seizures and a recorded prolonged asystole during an attack. The pacemaker was programmed to sensing only (ODO), single chamber ventricular pacing with hysteresis (VVI), and dual chamber pacing with rate drop response (DDD) for four month periods, with each patient allocated to one of the six possible sequences of these modes, according to chronological order of pacemaker implantation. The parent and patient were blinded to the pacemaker mode and asked to record all episodes of syncope or presyncope ("near miss" events). The doctor analysing the results was blinded to the patient and pacemaker mode.

RESULTS

One patient was withdrawn from the study after the pacemaker was removed because of infection. In the remaining children, both dual chamber and single chamber pacing significantly reduced the number of syncopal episodes compared with sensing only (p = 0.0078 for both). VVI was as effective as DDD for preventing syncope, but DDD was superior to VVI in reducing near miss events (p = 0.016).

CONCLUSIONS

Permanent pacing is an effective treatment for children with severe neurally mediated syncope and reflex anoxic seizures. VVI is as effective as DDD in preventing syncope and seizures, but DDD is superior in preventing overall symptoms.

Pharmacotherapy of neurally mediated syncope

A wide variety of pharmacological agents are currently used for prevention of recurrent neurally mediated syncope, especially the vasovagal faint. None, however, have unequivocally proven long-term effectiveness based on adequate randomized clinical trials. At the present time, beta-adrenergic receptor blockade, along with agents that increase central volume (eg, fludrocortisone, electrolyte-containing beverages), appear to be favored treatment options. The antiarrhythmic agent disopyramide and various serotonin reuptake blockers have also been reported to be beneficial. Finally, vasoconstrictor agents such as midodrine offer promise and remain the subject of clinical study. Ultimately, though, detailed study of the pathophysiology of these syncopal disorders and more aggressive pursuit of carefully designed placebo-controlled treatment studies are essential if pharmacological prevention of recurrent neurally mediated syncope is to be placed on a firm foundation.

Dual chamber pacing for neurally mediated syncope with a prominent cardioinhibitory component

The role of cardiac pacing for treatment of recurrent neurally mediated syncope (NMS) remains controversial. We hypothesized that dual chamber pacing in NMS patients with a prominent cardioinhibitory component may be beneficial. Twelve patients (mean age = 37.8+/-17 years, range 15-78 years, 7 men and 5 women) with a mean of 4+/-2.2 episodes of syncope underwent tilt table evaluation. Patients were passively tilted to 70 degrees head-up position for 20 minutes and then returned to the supine position. Isoproterenol was then infused at 1-2 microg/min to increase heart rate by > or = 25% and tilt was repeated. Patients lost consciousness after 16+/-6 minutes of tilt; nine patients had syncope in the baseline state and three during isoproterenol infusion. All patients had at least 5 seconds of asystole with a mean of 9.5+/-4 seconds (range 5-20 s). A dual chamber permanent pacemaker with a special feature allowing heart rate acceleration in response to bradycardia was implanted in all patients. During a mean follow-up of 18.6+/-4.2 months, 11 (92%) of these patients were free of syncope and had negative tilt table test. One (8%) patient had two episodes of syncope. We conclude that dual chamber pacing may be beneficial in patients with NMS with a prominent cardioinhibitory component.

Evolving indications for permanent pacing

Indications for permanent pacemakers have expanded in recent years. The American College of Cardiology (ACC) and American Heart Association (AHA) guidelines for implantation of cardiac pacemakers were recently updated and now include several of the newer indications. Greatest interest about newer applications of pacemaker therapy focuses on hypertrophic obstructive cardiomyopathy, dilated cardiomyopathy, and pacing for the prevention of atrial fibrillation. Pacing for neurocardiogenic syncope remains controversial despite emerging data. Pacing for long QT syndrome, pacing after cardiac transplantation, and pacing for hemodynamic improvement in the occasional patient with first-degree atrioventricular block and hemodynamic compromise also warrant attention. Available clinical data are discussed in the context of the recent ACC and AHA guidelines.

"Rate-drop response" cardiac pacing for vasovagal syncope. Rate-Drop Response Investigators Group

Recent reports suggest that cardiac pacing incorporating a rate-drop response algorithm is associated with a reduction in the frequency of syncopal episodes in patients with apparent cardioinhibitory vasovagal syncope. The detection portion of the algorithm employs a programmable heart rate change-time duration "window" to both identify abrupt cardiac slowing suggestive of an imminent vasovagal event and trigger "high rate" pacing. The purpose of this study was to develop recommendations for programming the rate-drop response algorithm. Pacemaker programming, symptom status, and drug therapy were assessed retrospectively in 24 patients with recurrent vasovagal syncope of sufficient severity to warrant consideration of pacemaker treatment. In the 53 +/- 19 months prior to pacing, patients had experienced an approximate syncope burden of 1.2 events/month. During follow-up of 192 +/- 160 days, syncope recurred in 4 patients (approximate syncope burden, 0.3 events/month, p < 0.05 vs. pre-pacing), and pre-syncope in 5 patients. In these patients, rate-drop response parameters were initially set based on electrocardiographic and/or tilt-table recordings, and were re-programmed at least once in 14 (58%) individuals. A 20 beat/min window height (top rate minus bottom rate), a window width of 10 beats (61% of patients), and 2 or 3 confirmation beats (79% of patients) appeared to be appropriate in most patients. Treatment intervention rate was set to > 100 beats/min in 89% of patients, with a duration of 1 to 2 min in 79%. In conclusion, a narrow range of rate-drop response parameter settings appeared to be effective for most individuals in this group of highly symptomatic patients.

The North American Vasovagal Pacemaker Study (VPS). A randomized trial of permanent cardiac pacing for the prevention of vasovagal syncope

OBJECTIVES

This study was done to evaluate pacemaker therapy for severe recurrent vasovagal syncope.

BACKGROUND

Nonrandomized studies have suggested that permanent pacing might help control the symptoms of recurrent vasovagal syncope. The study goal was to evaluate the effect of permanent pacemaker implantation on syncope in patients with frequently recurrent vasovagal syncope.

METHODS

Patients with > or = 6 lifetime episodes of syncope and with a tilt-table test that induced syncope or presyncope, as well as a relative bradycardia, were randomized to receive a dual-chamber pacemaker or not. The pacemaker prevented bradycardia and provided high-rate pacing if a predetermined drop in heart rate occurred (rate-drop response). The primary outcome was the first recurrence of syncope. Patients also completed a detailed diary recording presyncopal episodes.

RESULTS

A total of 284 patients was originally planned and a pilot study of 60 patients was initiated. At the planned first formal interim analysis of efficacy of the pilot study, an unanticipated large treatment effect was observed which fulfilled the prespecified criteria for early termination of the study. At that time, there were 54 patients enrolled, randomized evenly to no pacemaker or to pacemaker. In the no-pacemaker and pacemaker groups the mean ages were 40 and 46 years; 74% and 70% patients, respectively, were female. The baseline tilt-table test showed a slowest heart <60/min or longest heart period >1000 ms in 60% of no-pacemaker patients and 72% of pacemaker patients. There was a marked reduction in the postrandomization risk of syncope in pacemaker patients (relative risk reduction 85.4%, 95% confidence interval 59.7% to 94.7%; 2p=0.000022).

CONCLUSIONS

Dual-chamber pacing with rate-drop response reduces the likelihood of syncope in patients with recurrent vasovagal syncope.

Shortened head-up tilt testing potentiated with sublingual nitroglycerin in patients with unexplained syncope

BACKGROUND

Head-up tilt testing is extensively used to determine the vasovagal origin of syncope in patients with otherwise unexplained loss of consciousness, although issues remain regarding the method of the test. The diagnostic value of a shortened head-up tilt test potentiated with sublingual nitroglycerin was assessed in patients with unexplained syncope.

METHODS

Two hundred two patients (mean age 49+/-19 years) with syncope of unknown origin and 34 subjects in a control group (mean age 45+/-17 years) were studied. The patients and the subjects in the control group were tilted upright to 60 degrees for 20 minutes. If syncope did not occur, sublingual nitroglycerin (400 microg) was administered, and observation was continued for 25 more minutes.

RESULTS

During the unmedicated phase syncope occurred in 22 (11%) patients and in one member of the control group. After nitroglycerin was administered, syncope occurred in 119 (59%) patients and in 1 (3%) member of the control group. False-positive response (exaggerated response) was observed in eight (4%) patients and in four (12%) subjects in the control group. The total positivity rate of the test was 70% with a specificity rate of 94%.

CONCLUSIONS

Short-duration head-up tilt test potentiated with sublingual nitroglycerin provides an adequate specificity and positivity rate in patients with unexplained syncope.

Effect of dual-chamber pacing with automatic rate-drop sensing on recurrent neurally mediated syncope

We tested the hypotheses that a dual-chamber pacemaker that paces when intrinsic rate drops abruptly would reduce the number of syncopal spells and improve the quality of life in patients with highly recurrent neurally mediated syncope. Twelve patients with highly frequent neurally mediated syncope and at least 1 syncopal spell after tilt testing received dual-chamber pacemakers with automatic rate-drop sensing. The pacemakers were implanted 17+/-26 months after tilt testing, and the patients then were followed for 12+/-2 months. We compared the time to the first recurrence of syncope, syncope frequency, and quality of life for the 2 periods between tilt testing and pacemaker implantation, and between implantation and last follow-up. Only 6 of 12 patients fainted after pacemaker insertion. The median time to syncope recurrence before and after pacing was 7 days and 5.3 months, respectively. The geometric mean frequency of faints before and after pacing was 5.0 spells/month (95% confidence interval 2.7 to 9.2) and 0.30 spells/month (95% confidence interval 0.2 to 0.4), p <0.001. After 6 months the mean perception of health on the 100-point EuroQol scale rose from 55 to 82 (p = 0.003), and the general health perception on the SF-36 scale rose from 51 to 72 (p = 0.005). Permanent dual-chamber pacing with automatic rate-drop sensing in patients with highly frequent syncope is associated with a marked reduction in the likelihood of syncope and a marked improvement in quality of life.