Iatrogenic Chronotropic Incompetence and Exercise Tolerance in Heart Failure

Patients with CHF benefit from heart rate lowering, and the investigators have previously demonstrated that this does not adversely affect exercise tolerance. In a pacemaker population we also have shown that preventing heart rate lowering is detrimental in terms of symptoms and prognosis. The aim of the study is to therefore to establish whether heart rate limitation in patients with heart failure has a negative impact on exercise capacity. If the investigators establish that this is not the case, physicians will be able to confidently prescribe heart rate lowering agents, and programme pacemakers to allow bradycardia without the concern that there will be detrimental effects of symptom.

Each subject will undergo a full echocardiographic examination.We will assess LV systolic and diastolic function variables, mitral regurgitation, and pulmonary artery pressure.

Inclusion Criteria: Able to walk on a treadmill Able to provide consent Heart failure (or not) depending upon the arm. Patients with atrial fibrillation to have had an AV node ablation (or very slow response to AF) Exclusion Criteria: Cognitive impairment, known reaction to ivabradine, musculoskeletal issues limiting walking on a treadmill.