Pacing and vasovagal syncope: back to our physiologic roots

Excerpt

Enthusiasm for permanent cardiac pacing as a treatment for vasovagal syncope has ebbed and flowed for 30 years. Several case series conducted during the first decade of this period were strongly positive, culminating in randomized clinical trials conducted in Europe and North America. The first studies included patients randomized to receive a pacemaker versus those receiving conventional attempts at treatment. These studies all seemed to show a strong benefit [1]. A second series involved all patients receiving pacemakers, with some programmed to modes that were nearly off. These studies were single-blind, in that the treating physicians knew who received which programming and the patients did not; these results too were strongly positive [1]. In fact, they were so strongly positive that investigators were skeptical, and two formal double-blind randomized trials were subsequently conducted. Both of these latter studies featured all patients receiving pacemakers, with half the pacemakers essentially inactivated. Double blinding was maintained as much as possible, and the results of both studies were resoundingly negative. The earlier treatment effects all appeared to be due to a placebo effect, possibly including investigators unknowingly conveying more optimism to patients who received active pacing [1]. …