From the Guidelines
Flecainide can cause shortness of breath as a side effect, and patients should be closely monitored for respiratory symptoms, especially those with pre-existing heart failure or structural heart disease. This medication, which is used to treat certain types of abnormal heart rhythms (arrhythmias), may lead to respiratory symptoms in some patients [ 1 ]. Shortness of breath (dyspnea) is considered an uncommon but potentially serious side effect of flecainide. If you experience new or worsening shortness of breath while taking flecainide, you should contact your healthcare provider immediately as this could indicate a serious adverse reaction or worsening heart function.
Some key points to consider when prescribing flecainide include:
- Flecainide approximately doubles the likelihood of maintaining sinus rhythm [ 1 ]
- It can be safely administered in patients without significant structural heart disease, but should not be used in patients with coronary artery disease or in those with reduced LVEF [ 1 ]
- Precautions should be observed when using flecainide in the presence of intraventricular conduction delay, particularly left bundle branch block [ 1 ]
- Upon initiation of flecainide therapy, regular ECG monitoring is recommended to assess for potential risk of proarrhythmia [ 1 ]
Flecainide works by slowing electrical signals in the heart to stabilize heart rhythm, but it can sometimes affect heart function in ways that lead to fluid buildup in the lungs or reduced cardiac output, which manifests as breathing difficulty. Other respiratory side effects may include coughing or worsening of existing lung conditions. Patients with pre-existing heart failure or structural heart disease should be particularly cautious when taking flecainide, as they may be at higher risk for developing breathing problems.
From the FDA Drug Label
Dyspnea 10.3%
The following additional adverse experiences, possibly related to flecainide therapy and occurring in 1% to less than 3% of patients, have been reported in acute and chronic studies: ... Respiratory: pneumonitis/pulmonary infiltration possibly due to chronic flecainide treatment;
Flecainide and Shortness of Breath: Flecainide may cause shortness of breath, as indicated by the reported incidence of dyspnea (10.3%) in patients treated with flecainide. Additionally, there have been rare reports of pneumonitis/pulmonary infiltration possibly due to chronic flecainide treatment 2 2.
- Key Points:
- Dyspnea reported in 10.3% of patients
- Pneumonitis/pulmonary infiltration possibly due to chronic flecainide treatment
- Clinical Decision: Flecainide may cause shortness of breath, and patients should be monitored for respiratory adverse effects.
From the Research
Flecainide and Shortness of Breath
- There is no direct evidence in the provided studies that flecainide causes shortness of breath as a common side effect 3, 4, 5, 6, 7.
- However, one study mentions a case of pulmonary oedema associated with atrial fibrillation with rapid ventricular response on flecainide 5.
- Another study notes that patients who did not clinically benefit from Class Ic antiarrhythmics, including flecainide, more often underwent pulmonary vein isolation, but it does not specifically mention shortness of breath as a reason 7.
- The studies primarily focus on the efficacy and safety of flecainide in treating atrial fibrillation and supraventricular tachycardias, with common side effects including neurologic signs, central and peripheral, and gastrointestinal effects 5, 6, 7.
- Proarrhythmic effects are a concern with flecainide, particularly in patients with structural heart disease, but shortness of breath is not explicitly listed as a common adverse event 3, 4, 7.