How to manage bradycardia in a patient with dengue?

Management of Bradycardia in Dengue Fever

Bradycardia in dengue fever is a reversible infectious cause that requires supportive management focused on treating the underlying dengue infection, with pharmacologic intervention reserved only for patients with symptomatic bradycardia causing hemodynamic compromise. 1

Initial Assessment and Recognition

Dengue fever is explicitly listed as a reversible cause of sinus node dysfunction in ACC/AHA/HRS guidelines, appearing alongside other infections like Lyme disease, malaria, and viral hemorrhagic fevers. 1 This classification is critical because it fundamentally changes the management approach—the primary treatment is addressing the dengue infection itself, not the bradycardia.

Key Clinical Features to Assess

• Determine if bradycardia is causing symptoms or hemodynamic compromise: altered mental status, ischemic chest discomfort, acute heart failure, hypotension (systolic BP <80 mmHg), syncope, dizziness, or signs of shock. 1, 2
• Bradycardia in dengue is extremely common (19.7% in one series) and typically benign, often occurring despite fever when tachycardia would normally be expected. 3
• Cardiac involvement in dengue can range from isolated sinus bradycardia to myocarditis (13% in severe dengue), conduction blocks, and even fulminant myocarditis with reduced ejection fraction (<40% in 13.1% of patients). 4, 5, 3

Management Algorithm

Step 1: Asymptomatic or Minimally Symptomatic Bradycardia

For asymptomatic bradycardia in dengue, no specific cardiac treatment is required—focus entirely on supportive dengue management with fluid resuscitation per WHO guidelines, as the bradycardia will resolve with recovery from the infection. 1, 5

• Asymptomatic sinus bradycardia has not been associated with adverse outcomes and requires only observation. 1
• Most conduction disturbances in dengue are benign and transient, resolving spontaneously without long-term complications like dilated cardiomyopathy. 5

Step 2: Symptomatic Bradycardia Requiring Acute Intervention

If the patient develops symptomatic bradycardia with hemodynamic compromise, initiate the standard bradycardia protocol while continuing dengue-specific supportive care:

First-Line: Atropine

• Administer atropine 0.5-1 mg IV push, repeated every 3-5 minutes up to a maximum total dose of 3 mg. 1, 2, 6
• Doses less than 0.5 mg may paradoxically worsen bradycardia through a transient vagal stimulation phase and must be avoided. 1, 6
• Atropine works by blocking muscarinic receptors and abolishing vagal cardiac slowing, making it effective for sinus bradycardia and AV nodal blocks. 1, 6

Second-Line: Chronotropic Infusions (if atropine fails)

• Dopamine 5-10 mcg/kg/min IV infusion is the preferred second-line agent, providing both chronotropic (heart rate increase) and inotropic (contractility increase) effects. 1, 7, 2
• Start dopamine at 5 mcg/kg/min and increase by 5 mcg/kg/min every 2 minutes, titrating to heart rate response and blood pressure, with a maximum of 20 mcg/kg/min to avoid excessive vasoconstriction and arrhythmias. 1, 2
• Alternative: Isoproterenol 20-60 mcg IV bolus or 1-20 mcg/min infusion may be considered in patients at low risk for coronary ischemia, as it provides chronotropic and inotropic effects without vasoconstriction. 1, 7
• Epinephrine 2-10 mcg/min IV infusion is reserved for severe hypotension requiring both strong chronotropic and inotropic support. 1, 2

Third-Line: Transcutaneous Pacing

• Apply transcutaneous pacing immediately for unstable patients who remain hemodynamically compromised despite atropine, as this is a Class IIa recommendation for symptomatic bradycardia unresponsive to medications. 1, 2
• Transcutaneous pacing serves as a temporizing measure while preparing for potential transvenous pacing if needed, though most dengue-related bradycardia resolves with supportive care. 2

Step 3: Evaluate for Myocardial Involvement

In dengue patients with bradycardia, obtain:

• 12-lead ECG to assess for conduction abnormalities beyond sinus bradycardia (AV blocks, ST-segment changes suggesting myocarditis). 8, 5, 3
• Cardiac biomarkers (troponin-T, CK-MB, NT-pro BNP) if myocarditis is suspected, as elevated levels predict adverse outcomes. 3, 9
• 2D echocardiography to assess left ventricular function, particularly if troponins are elevated or clinical signs of heart failure are present. 3, 9

Patients with ECG abnormalities, elevated cardiac markers, or reduced ejection fraction have significantly higher mortality risk (all 14 deaths in one series had these abnormalities), while absence of these findings has 100% negative predictive value. 3

Critical Warnings and Pitfalls

Avoid Unnecessary Permanent Pacing

• Do NOT proceed to permanent pacemaker implantation for bradycardia during acute dengue infection, as this is a reversible cause that will resolve with treatment of the underlying infection. 1
• Temporary pacing may be required in rare cases (as documented in one case requiring temporary pacemaker for 8 days), but permanent pacing is inappropriate. 8

Recognize Dengue-Specific Cardiac Complications

• Dengue can cause fulminant myocarditis masquerading as acute coronary syndrome with ST-segment depression and elevated troponin, but this is typically reversible with supportive care. 8, 9
• Acute pulmonary edema may develop from myocardial dysfunction, requiring careful fluid management to balance dengue-related capillary leak syndrome with cardiac dysfunction. 4, 9

Monitor for Progression

• Continuous cardiac monitoring is essential as conduction abnormalities can progress from benign bradycardia to higher-degree AV blocks or ventricular arrhythmias. 5, 3
• Transfer to ICU is indicated if continuous chronotropic infusions are required or if signs of myocarditis with hemodynamic compromise develop. 2

Prognosis and Recovery

Most cardiac manifestations in dengue, including bradycardia, are transient and resolve completely within days to weeks without long-term sequelae. 5 Unlike other viral myocarditis (such as hepatitis C), dengue does not cause chronic dilated cardiomyopathy. 5 The key is recognizing dengue as the reversible etiology and providing appropriate supportive care while avoiding permanent interventions for what is fundamentally a temporary condition.