Pacing for neurally mediated syncope: is placebo powerless?
BACKGROUND
After two recent controlled trials failed to prove superiority of cardiac pacing over placebo in patients affected by neurally mediated syncope, a widely accepted opinion is that cardiac pacing therapy is not very effective and that a strong placebo effect exists.


OBJECTIVE
To measure the effect of placebo pacing therapy.


RESULTS
We compared the recurrence rate of syncope during placebo vs. no treatment in controlled trials of drug or pacing therapy. Syncope recurred in 38% of 252 patients randomized to placebo pooled from five trials vs. 34% of 881 patients randomized to no treatment pooled from eight trials. The corresponding recurrence rate with active cardiac pacing was 15% in 203 patients from six trials.


CONCLUSIONS
Placebo is not an effective therapy for neurally mediated syncope. Different selection criteria in patients who are candidates for cardiac pacing-for example, presence, absence, or severity of the cardioinhibitory reflex may separate positive from negative trials.
Brignole
M
M
Department of Cardiology, Ospedali del Tigullio, Via don Bobbio, 16033 Lavagna, Italy. mbrignole@ASL4.liguria.it
Sutton
R
R
D005500:Follow-Up Studies; D006801:Humans; D010138:Pacemaker, Artificial / Q000523:psychology*; D015990:Placebo Effect; D010919:Placebos; D016032:Randomized Controlled Trials as Topic; D012008:Recurrence; D013575:Syncope / Q000523:psychology* / Q000628:therapy*; D016896:Treatment Outcome
D010919:Placebos