From the Guidelines
Chronotropic incompetence is a condition that should be treated with a dual-chamber rate-responsive pacemaker in patients with symptomatic chronotropic incompetence that significantly impacts quality of life, as it can substantially improve exercise capacity and quality of life in affected individuals. This condition occurs due to dysfunction in the sinoatrial node, autonomic nervous system, or beta-adrenergic receptors, and common causes include aging, heart failure, coronary artery disease, and medications like beta-blockers 1. Symptoms of chronotropic incompetence include fatigue, shortness of breath, dizziness, and reduced exercise tolerance.
Diagnosis and Treatment
Diagnosis of chronotropic incompetence involves exercise stress testing, which is integral to the diagnosis of this condition, as it can help identify an inability to increase heart rate commensurate with the increased metabolic demands of physical activity 1. Treatment options for chronotropic incompetence include medication adjustment, exercise training, and pacemaker implantation for severe cases. Rate-responsive pacemakers are particularly effective as they can detect physical activity and adjust heart rate accordingly.
Importance of Treatment
Proper treatment of chronotropic incompetence is important as it can substantially improve exercise capacity and quality of life in affected individuals. According to the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay, exercise electrocardiographic testing is crucial in the diagnosis of chronotropic incompetence 1. Additionally, the 2012 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities recommends permanent cardiac pacing as the only effective treatment for symptomatic bradycardia, which is often associated with chronotropic incompetence 1.
Pacemaker Selection
For patients with symptomatic chronotropic incompetence, a dual-chamber rate-responsive pacemaker is often recommended, as it can provide rate adaptive pacing, which can help improve exercise tolerance and quality of life 1. However, rate adaptive programming should be recommended only for patients with evidence of significant symptomatic chronotropic incompetence and demonstrated improvement following programming the rate adaptive feature, as it may increase the risk of atrial fibrillation in some patients 1.
Key Points
- Chronotropic incompetence is a condition that occurs due to dysfunction in the sinoatrial node, autonomic nervous system, or beta-adrenergic receptors.
- Common causes include aging, heart failure, coronary artery disease, and medications like beta-blockers.
- Symptoms include fatigue, shortness of breath, dizziness, and reduced exercise tolerance.
- Diagnosis involves exercise stress testing.
- Treatment options include medication adjustment, exercise training, and pacemaker implantation for severe cases.
- Rate-responsive pacemakers are particularly effective in treating chronotropic incompetence.
- A dual-chamber rate-responsive pacemaker is often recommended for patients with symptomatic chronotropic incompetence that significantly impacts quality of life.
From the Research
Definition and Diagnosis of Chronotropic Incompetence
- Chronotropic incompetence is defined as the inability to increase and maintain heart rate appropriately during exercise 2.
- It is characterized by a lack of cardiac acceleration during exercise, resulting in intolerance to exertion 2, 3.
- Diagnosis is based on clinical symptoms, demonstration of a lack of cardiac acceleration during exercise, and the presence of another indication for pacing 2.
Causes and Associations of Chronotropic Incompetence
- Chronotropic incompetence is often seen in subjects with chronic congestive heart failure (CHF) 4.
- The prevalence of chronotropic incompetence is highest in those with most impaired exercise capacity 4.
- It is associated with reduced peak oxygen consumption, and rate-responsive pacing therapy is under investigation to improve exercise capacity in heart failure (HF) 5.
- Beta-blocker use is not the primary cause of chronotropic incompetence, as acute beta-blocker cessation does not normalize the chronotropic response to exercise in patients with advanced HF and chronotropic incompetence 5.
Predictors and Treatment of Chronotropic Incompetence
- Predictors of chronotropic incompetence include existence of coronary artery disease, presence of an acquired valvular heart disease, and former cardiac surgery 6.
- Chronic antiarrhythmic therapy with digitalis, beta blockers, and amiodarone are significant predictors of chronotropic incompetence 6.
- Treatment options include rate-modulating pacing systems, such as adding an atrial lead in a patient in complete AV block and VVI pacing 2.
- Rate-adaptive sensors, including motion sensors, respiration sensors, QT interval, and right ventricular contractility, can also be used to correct chronotropic incompetence 2.