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Placebo effect of pacemaker implantation in obstructive hypertrophic cardiomyopathy. PIC Study Group. Pacing In
C Linde1, F Gadler, L Kappenberger
1Department of Cardiology, Karolinska Hospital, Stockholm, Sweden.
Insights
Pacemaker implantation in obstructive hypertrophic cardiomyopathy (HC) showed a placebo effect, improving symptoms and reducing outflow tract obstruction. Active pacing provided greater benefits than inactive pacing.
Area of Science:
- Cardiology
- Medical Devices
- Clinical Trials
Background:
- Obstructive hypertrophic cardiomyopathy (HC) presents challenges in managing symptoms and left ventricular (LV) outflow tract obstruction.
- Pacemaker implantation is a potential intervention, but its effects, including placebo responses, require thorough evaluation.
Purpose of the Study:
- To evaluate the placebo effect of pacemaker implantation in patients with obstructive HC.
- To compare the efficacy of atrioventricular (AV) synchronous pacing with optimal AV delay versus inactive pacing.
Main Methods:
- A 3-month, multicenter, double-blind, randomized cross-over study.
- 40 patients initially received inactive pacing, followed by active pacing, while 41 patients underwent the reverse sequence.
- Evaluated quality of life, LV outflow tract obstruction, and perceived symptoms.
Main Results:
- Inactive pacing led to significant improvements in chest pain, dyspnea, palpitations, and a decrease in LV outflow tract gradient.
- Active pacing resulted in a more pronounced reduction in the LV outflow tract gradient and greater improvements in symptoms, alertness, autonomy, and exercise capacity.
- Perceived symptom improvements did not significantly differ between active and inactive pacing groups.
Conclusions:
- Pacemaker implantation demonstrated a placebo effect on both objective and subjective parameters in patients with obstructive HC.
- While placebo effects are evident, active pacing offers superior benefits for LV outflow tract obstruction and functional capacity in this patient population.
Abstract:
This study evaluated a possible placebo effect by pacemaker implantation. The study design was a 3-month multicenter, double-blind, randomized cross-over study to compare the effects of atrioventricular (AV) synchronous pacing with an optimal AV delay to inactive pacing in patients with obstructive hypertrophic cardiomyopathy (HC). Quality of life and left ventricular (LV) outflow tract obstruction were evaluated after the first study period in 40 patients assigned to inactive pacing. Data were compared with the corresponding results among the 41 subjects assigned to a first study period of active pacing. During inactive pacing, there was a significant improvement in perceived chest pain, dyspnea, and palpitations. Moreover, LV outflow tract gradient decreased from 71 +/- 32 mm Hg to 52 +/- 34 mm Hg (p = 0.04). In patients assigned to active pacing the reduction of the gradient was significantly more pronounced (70 +/- 24 mm Hg to 33 +/- 27 mm Hg; p <0.0001). The difference in gradient reduction between the groups was highly significant (p <0.00001). In the group assigned to active pacing there was also significant improvement in perceived symptoms as well as in alertness, the ability to be self-autonomous, and strenuous physical exercise. The improvements in the latter were significantly greater in those paced actively compared with patients paced inactively, whereas the changes in perceived symptoms did not differ between groups. In conclusion, pacemaker implantation had a placebo effect on objective and subjective parameters in this group of patients with obstructive HC.