What causes coughing after lying down in a patient with an Automated Implantable Cardioverter-Defibrillator (AICD)?

Causes of Coughing After Lying Down in a Patient with AICD

The most likely cause of coughing after lying down in a patient with an Automated Implantable Cardioverter-Defibrillator (AICD) is heart failure with pulmonary congestion, which can worsen in the supine position due to increased venous return to the heart. 1

Primary Cardiac Causes

• Heart failure is a common condition in patients with AICDs and can cause coughing, particularly when lying down, as fluid redistribution increases pulmonary congestion 1
• Pulmonary edema, whether cardiogenic or noncardiogenic, can cause cough that may be the sole presenting manifestation of congestive heart failure 1
• Patients with heart failure often experience worsening of symptoms in the supine position due to increased venous return and subsequent pulmonary congestion 1

Medication-Related Causes

• ACE inhibitors, commonly prescribed for heart failure patients with AICDs, can cause a persistent dry cough in approximately 5-10% of white patients and up to 50% in Chinese patients 1
• The ACE inhibitor-induced cough is characteristically nonproductive, accompanied by a persistent "tickle" in the throat, appears within the first months of therapy, and resolves within 1-2 weeks of discontinuation 1
• It's important to rule out pulmonary congestion before attributing cough to ACE inhibitor therapy, as heart failure itself can cause cough 1

Mechanical/Device-Related Causes

• The AICD device itself may cause mechanical irritation to surrounding tissues, particularly when the patient is lying down, potentially triggering a cough reflex 1
• Mediastinal lesions or devices (like an AICD) may impinge on adjacent airways and lead to chronic cough, especially in certain positions 1
• Patients with AICDs may experience physical awareness of the device, which can include sensations that trigger cough when lying down 2

Other Potential Causes

• Gastroesophageal reflux disease (GERD) can worsen when lying down and may cause cough without typical gastrointestinal symptoms in up to 75% of cases 3
• Postnasal drip syndrome may cause cough that worsens in the supine position due to mucus accumulation 3
• Interstitial lung disease, which can be present in patients with cardiac conditions, may cause chronic cough that can be exacerbated by position changes 1

Diagnostic Approach

• Assess for progression of underlying heart failure, including checking for other signs of fluid overload 1
• Review medication list for ACE inhibitors and consider a trial of discontinuation if appropriate 1
• Consider chest imaging to evaluate for pulmonary edema, interstitial changes, or device-related complications 1
• If cough persists despite optimal heart failure management and ACE inhibitor discontinuation, consider evaluation for GERD, postnasal drip, or other pulmonary conditions 1

Management Considerations

• Optimize heart failure therapy to reduce pulmonary congestion, which may resolve positional cough 1
• If ACE inhibitor-induced cough is suspected, consider switching to an angiotensin receptor blocker (ARB) 1
• For persistent cough despite addressing cardiac causes, consider treatments for unexplained chronic cough according to guidelines, such as gabapentin or speech pathology therapy 1
• In cases of intractable cough affecting quality of life, low-dose opiates may be considered for symptom control with careful monitoring of benefits and risks 1

Pitfalls and Caveats

• Don't assume cough is always due to the AICD itself; underlying heart failure is a more common and potentially serious cause 1
• Avoid attributing cough solely to ACE inhibitors without first ruling out worsening heart failure 1
• Be cautious with supplemental oxygen therapy in patients with heart failure and cough, as it may mask hypoventilation without treating the underlying cause 1
• Remember that cough may be multifactorial in patients with cardiac devices, requiring a comprehensive approach to management 1