Title : An unusual presentation of sinus bradycardia in acute pericarditis: A case report
Abstract:
Background: Sinus tachycardia is the most common arrhythmia associated with acute pericarditis due to increased sympathetic drive from pain and inflammation. However, sinus bradycardia is rarely reported in association with pericarditis. An uncommon finding in this situation is bradycardia, which could be caused by elevated vagal tone, due to pericardial irritation. We highlight the significance of identifying benign origins of bradycardia in the absence of ischaemia or structural cardiac abnormalities by presenting the case of a young female who experienced transitory sinus bradycardia in the setting of acute pericarditis.
Case Presentation: A 29-year-old previously healthy female presented to the emergency department with acute-onset pleuritic chest pain that worsened with inspiration and improved when leaning forward. She denied any history of syncope, palpitations, or exertional dyspnoea. Two weeks before this presentation, she had an upper respiratory tract infection characterized by fever, sore throat, and myalgia. She was mildly hypotensive which responded well to IV fluids, other than that she was haemodynamically stable. Her ECG showed Sinus Bradycardia with a rate of 42/min with no ischaemic changes with normal blood tests. High-sensitivity troponin levels were within the normal range, ruling out acute myocardial infarction or myocarditis. Thyroid function tests were also normal, excluding hypothyroidism as a cause of bradycardia. A CTPA ruled out PE. The scan revealed a mild pericardial and pleural effusion without evidence of pulmonary embolism. Transthoracic echocardiography showed a minimal pericardial effusion with normal left ventricular function and no signs of tamponade. Given the absence of ischemic risk factors, normal troponin levels, and the history of a preceding viral illness, the diagnosis of acute pericarditis was established. It is speculated that her bradycardia was a response to irritation to pericardium and high vagal tone. She was managed conservatively with NSAIDs and Colchicine as an outpatient. She remained asymptomatic from a hemodynamic standpoint, and no further intervention was required. She had a follow up after two weeks where she was asymptomatic, and her ECG was reverted to normal sinus rhythm with a rate of 84b/min. No further investigations were carried out.
Discussion: Bradycardia, an uncommon symptom of pericarditis, is probably brought on by excessive vagal activation because of pericardial irritation. The vagus nerve innervates the heart and pericardium, and inflammation in the pericardium can cause a parasympathetic reaction that results in sinus bradycardia. Rare instances of bradycardia have been documented in the literature, even though pericarditis is most frequently linked to sinus tachycardia because of pain and inflammation. It is essential to rule out life-threatening conditions such as myocardial infarction, myocarditis, and hypothyroidism when evaluating bradycardia in pericarditis. In this case, normal troponin levels, a preserved ejection fraction on echocardiography, and an absence of ischemic risk factors helped exclude more concerning aetiologies.
Conclusion: A vagal reaction is probably the cause of this case's unusual presentation of acute pericarditis with sinus bradycardia. Clinicians can prevent needless tests and treatments by recognising this uncommon yet benign symptom. It is essential to be aware of these unusual manifestations to diagnose and treat pericarditis promptly.
