A Randomized Trial of Closed Loop Stimulation After Epicardial Pacemaker Implantation for Congenital Heart Disease

Sinus node dysfunction is highly prevalent among patients with congenital heart disease, manifesting as resting bradycardia or chronotropic incompetence. As children and adults with congenital heart disease are now expected to have increasing life-expectancy; with well over 1 million adult patients currently living in North America,1 issues such as mental health, acquired comorbidities and their impact on overall cardiovascular health have assumed increased scrutiny.

It is now understood that objective measures of aerobic capacity, such as peak VO2, peak VE/VCO2, and heart rate reserve predict all-cause mortality for adult patients with congenital heart disease. As the chronotropic response during exercise is a key determinant of aerobic capacity, improvement in sensor-based technology for heart rate support is expected to have a significant impact on functional capacity and longevity in this population. Some forms of congenital heart disease, such as single ventricle physiology after the Fontan population are especially likely to benefit, as cardiac output is determined almost exclusively by heart rate during exertion due to limited ability to augment cardiac stroke volume.2

It is also becoming increasingly clear that sedentary behaviors are highly relevant to overall cardiovascular health in the general adult population. Adult patients with congenital heart disease are at especially high risk for sedentary behavior as a result of 1) chronic restriction for physical activities based on ill-founded medical advice, 2) chronotropic incompetence resulting from prior surgical palliations and hemodynamic stressors, and 3) overestimation of physical activity.

5.0 Enrollment/Randomization

Patient Enrollment: The treating physician will identify potential subjects with a previously implanted pacemaker and present a brief overview of the study; if the subject is interested, the study will be described in detail. Informed consent will be obtained by the investigator after discussing the study, including the voluntary nature of participation and notification the subject can withdraw at any time. Ample time for questions and answers will be allowed. The investigator will give the subject and his/her legal guardian the opportunity to take the consent home to think about it more, with the option to call or meet with the investigator to ask additional questions. If the subject and/or his/her parent/legal guardian agree to participate, the investigator will ask them to sign a written, informed consent and assent. A copy of the assent and consent will be given to the subject and/or his/her parent/legal guardian.