What medication should be given to a patient with sinus tachycardia?

Management of Sinus Tachycardia

For sinus tachycardia, identify and treat the underlying cause first—no specific medication is required for physiologic sinus tachycardia, but if symptomatic rate control is needed, metoprolol is the first-line agent. 1, 2

Critical First Step: Treat the Underlying Cause, Not the Heart Rate

The most important principle is that sinus tachycardia is almost always a physiologic response to an underlying condition, and "normalizing" the heart rate can be detrimental, especially when cardiac output depends on compensatory tachycardia. 1

Common triggers requiring treatment include:

• Fever, infection, dehydration, anemia 2, 3
• Pain or anxiety 2
• Hypoxia, hyperthyroidism, heart failure 2
• Medications: albuterol, aminophylline, caffeine, stimulants, atropine, catecholamines 2, 3
• Recreational drugs: amphetamines, cocaine, ecstasy, cannabis 3

Initial evaluation must focus on oxygenation status—assess for increased work of breathing (tachypnea, retractions, paradoxical abdominal breathing) and pulse oximetry, providing supplemental oxygen if needed. 1

When to Give Medication for Rate Control

Indications for Pharmacologic Treatment

Medication is appropriate only when:

• The patient is symptomatic (palpitations, chest discomfort, dizziness) despite treating reversible causes 2, 3
• The tachycardia is causing rate-related cardiovascular compromise (acute altered mental status, ischemic chest discomfort, acute heart failure, hypotension, shock) 1
• The diagnosis is inappropriate sinus tachycardia (IST) rather than physiologic sinus tachycardia 2, 3, 4

Critical caveat: With ventricular rates <150 bpm in the absence of ventricular dysfunction, the tachycardia is more likely secondary to the underlying condition rather than the cause of instability—treat the cause, not the rate. 1

Medication Algorithm for Symptomatic Sinus Tachycardia

First-Line: Beta-Blockers (Metoprolol)

Metoprolol is the preferred agent for acute PRN management of symptomatic sinus tachycardia, per American College of Cardiology recommendations. 2

Dosing:

• IV metoprolol for acute rate control when IV access is available 2
• Oral metoprolol when IV access is unavailable, particularly combined with vagal maneuvers 2
• For chronic management: metoprolol succinate 50 mg once daily, titrate up to 200 mg daily as tolerated 2
• Alternative: metoprolol tartrate 100-200 mg daily in 2 divided doses 2

Why metoprolol is preferred:

• Particularly effective for stress-related and anxiety-triggered tachycardia 2, 3
• Provides prognostic benefit post-myocardial infarction and in heart failure 2, 3
• Beta-1 selective, minimizing bronchospasm risk 2

Important limitation: Beta-blockers are often poorly tolerated in IST due to hypotension, and even at high doses may be ineffective. 2, 4

Second-Line: Calcium Channel Blockers (Diltiazem)

IV diltiazem is reasonable when beta-blockers are contraindicated or ineffective. 2, 5

Dosing:

• IV bolus: 10 mg (0.1-0.2 mg/kg ideal body weight) given slowly 5
• IV infusion: start at 5-10 mg/hr, increase up to 30 mg/hr as needed to achieve heart rate <100 bpm 5
• Target heart rate typically achieved in 2 hours at mean infusion rate of 13.3 mg/hr 5

Diltiazem is particularly useful in hyperthyroidism when beta-blockers are contraindicated. 2

Critical safety warning: Avoid IV calcium channel blockers in patients with systolic heart failure, hypotension, or when combined with IV beta-blockers due to potentiation of hypotensive/bradycardic effects. 2

Alternative Agents for Refractory Cases

For inappropriate sinus tachycardia refractory to beta-blockers, ivabradine (5-7.5 mg twice daily) is more effective than metoprolol for symptom relief during exercise and daily activity, with 70% of patients becoming symptom-free. 2, 6, 7

Ivabradine is a specific sinus node If "funny current" inhibitor that reduces heart rate without negative inotropic effects. 6, 7

Common Pitfalls to Avoid

Do not use adenosine for sinus tachycardia—it is ineffective because sinus tachycardia is not a reentrant rhythm. 2

Do not confuse sinus tachycardia with other narrow-complex tachycardias (AVNRT, atrial tachycardia, atrial flutter)—these require different management. 2, 8

Do not abruptly discontinue beta-blockers—taper to avoid rebound tachycardia and hypertension. 2

Avoid non-selective beta-blockers (propranolol, nadolol) in patients with reactive airway disease due to unacceptable bronchospasm risk. 2

In patients with asthma, start with low-dose cardioselective agents: metoprolol 12.5-25 mg twice daily, monitoring closely for bronchospasm. 2

When Medication is Inappropriate

Hemodynamically unstable patients require immediate synchronized cardioversion, not pharmacologic rate control. 1, 2

Physiologic sinus tachycardia with a correctable cause should be managed by treating the underlying trigger rather than suppressing the compensatory tachycardia. 1, 2

Postural orthostatic tachycardia syndrome (POTS) must be distinguished from IST—rate suppression may cause severe orthostatic hypotension in POTS. 2, 8

Special Consideration: Inappropriate Sinus Tachycardia (IST)

IST is characterized by persistent resting heart rate >100 bpm with excessive rate increase during activity and nocturnal normalization on 24-hour Holter monitoring. 2, 3

IST predominantly affects healthcare professionals and females (90%) with mean age around 38 years. 3, 4

Diagnosis requires 12-lead ECG showing P waves positive in leads I, II, aVF; negative in aVR, with P wave axis 0-90 degrees. 3

Long-term outcome of IST is benign, so treatment may be unnecessary unless symptoms are intolerable. 4