Clinical Trial: The Influence of Heart Rate Limitation on Exercise Tolerance in Pacemaker Patients.

Study Status: Completed
Recruit Status: Unknown status
Study Type: Interventional

Official Title: The Influence of Iatrogenic Chronotropic Incompetence on Exercise Tolerance in Pacemaker Patients With Chronic Heart Failure.

Brief Summary: To examine the effects of heart rate reduction on exercise capacity in control subjects and patients with chronic heart failure.

Detailed Summary:

Original proposal: Does iatrogenic chronotropic incompetence lead to impaired exercise capacity in patients with CHF

Aim The aim of this proposal is to examine the effects of iatrogenic CI on exercise capacity in control subjects and patients with chronic heart failure.

Hypothesis Iatrogenic chronotropic incompetence does not contribute significantly to reductions in exercise capacity in patients with heart failure or control subjects with pacemakers.

Methods REDUCING HEART RATE AT REST AND EXERCISE In patients with sinus rhythm, the present proposal utilizes a heart failure medication called ivabradine. This agent, an If channel blocker, specifically targets the sinus node leading to a slower heart rate. The agent is approved and licensed for use in patients with heart failure at the doses proposed. Ivabradine slows the sinus rate with none of the peripheral effects of beta-blockers. Heart rate lowering with ivabradine improves cardiac function, and outcomes related to the degree of bradycardia achieved.

In patients with atrial fibrillation, the present proposal will recruit patients with CRT and atrial fibrillation that have undergone atrio-ventricular node (AVN) ablation to improve the efficacy of CRT. Patients who have undergone AVN ablation are dependent upon their pacemaker, and we can therefore control their heart rate accurately.

SUBJECT SELECTION Inclusion criteria We will only include patients able to give informed written consent, which will be obtained in all subjects, and those capable of performing a peak exercise test. Since we are performing the study on three groups of patients, further inclusion criteria for each group are outlined below.

Comparing cardiopulmonary exercise testing performance