What medication is recommended for a patient with tachycardia and palpitations, considering potential underlying conditions such as hypertension or angina?

Medication for Tachycardia and Palpitations

First-Line Treatment: Beta-Blockers

Beta-blockers are the most appropriate first-line medication for treating palpitations and tachycardia, particularly metoprolol (25-100 mg twice daily), atenolol (25-100 mg daily), or propranolol (10-40 mg three to four times daily), as they effectively control heart rate without causing hypotension in most patients. 1, 2

Why Beta-Blockers Are Preferred

• Beta-blockers provide dual benefit for patients with both palpitations and hypertension, treating both conditions simultaneously 1
• They have minimal proarrhythmic risk compared to Class I antiarrhythmic drugs (quinidine, disopyramide, flecainide), which may increase mortality 3
• Beta-blockers can be titrated to control heart rate with minimal blood pressure impact in normotensive patients, unlike calcium channel blockers 1
• They are particularly effective for palpitations associated with anxiety or increased adrenergic tone, which is common in symptomatic patients 1, 2

Specific Beta-Blocker Recommendations by Clinical Scenario

For acute symptomatic tachycardia (hemodynamically stable):

• Metoprolol 2.5-5 mg IV bolus over 2 minutes, up to 3 doses 4
• Esmolol 500 mcg/kg IV bolus over 1 minute, then 50-300 mcg/kg/min infusion (ultra-short acting for rapid titration) 4
• Propranolol 1 mg IV over 1 minute, up to 3 doses at 2-minute intervals 4

For chronic/ongoing management:

• Metoprolol tartrate 25-100 mg twice daily (immediate release) 4, 1
• Metoprolol succinate 50-400 mg once daily (extended release) 4, 1
• Atenolol 25-100 mg once daily 4
• Propranolol 10-40 mg three to four times daily 4

Second-Line Options: Calcium Channel Blockers

If beta-blockers are contraindicated or ineffective, non-dihydropyridine calcium channel blockers (verapamil or diltiazem) are reasonable alternatives, particularly for supraventricular tachycardia. 4

Calcium Channel Blocker Dosing

For acute treatment:

• Diltiazem 0.25 mg/kg IV bolus over 2 minutes, then 5-15 mg/hour infusion 4
• Verapamil 0.075-0.15 mg/kg IV bolus over 2 minutes 4

For chronic management:

• Diltiazem 120-360 mg once daily (extended release) 4
• Verapamil 180-480 mg once daily (extended release) 4

Critical Contraindications for Calcium Channel Blockers

• Decompensated heart failure (non-dihydropyridines worsen HF) 4
• Pre-excitation syndromes with atrial fibrillation (Wolff-Parkinson-White syndrome) 4
• Severe left ventricular dysfunction (LVEF <40%) 2
• Concomitant use with IV beta-blockers (risk of severe hypotension and bradycardia) 4

Third-Line Options: Antiarrhythmic Drugs

For patients with documented supraventricular arrhythmias who fail beta-blockers and calcium channel blockers, consider Class IC antiarrhythmics (flecainide or propafenone) only if there is no structural heart disease. 4

Class IC Antiarrhythmic Dosing

Flecainide:

• Start 50 mg every 12 hours 4, 5
• Maximum 300 mg/day for paroxysmal supraventricular arrhythmias 5
• Increases should occur no more frequently than every 4 days 5

Propafenone:

• Start 150 mg every 8 hours (immediate release) or 225 mg every 12 hours (extended release) 4
• Maximum 300 mg every 8 hours (immediate release) or 425 mg every 12 hours (extended release) 4

Absolute Contraindications for Class IC Drugs

• Structural heart disease (including ischemic heart disease, prior MI, cardiomyopathy) 4
• Left bundle branch block 4
• Sinus or AV conduction disease without pacemaker 4
• Atrial flutter unless combined with AV nodal blocking agents (risk of 1:1 conduction) 4
• Brugada syndrome 4

Fourth-Line: Amiodarone

Amiodarone is reserved for refractory cases or patients with structural heart disease where other agents are contraindicated, but it carries significant long-term toxicity risks. 4

• Loading: 400-600 mg daily in divided doses for 2-4 weeks 4
• Maintenance: 100-200 mg daily 4
• Monitor for thyroid dysfunction, pulmonary fibrosis, hepatic toxicity, and corneal deposits 4

Critical Decision Points Before Treatment

Mandatory Diagnostic Workup

Before initiating antiarrhythmic therapy, obtain:

• 12-lead ECG during symptoms to identify the specific arrhythmia 4, 1
• Ambulatory ECG monitoring (Holter or event recorder) for recurrent palpitations 1
• Echocardiography to evaluate for structural heart disease 1
• Thyroid function tests to exclude hyperthyroidism 4

Identify the Underlying Rhythm

The treatment algorithm depends on QRS width and regularity: 4

Narrow-QRS tachycardia (QRS <0.12 seconds):

• Most likely supraventricular in origin 4
• Beta-blockers or calcium channel blockers are appropriate 4
• Adenosine 6 mg rapid IV push (then 12 mg if needed) for acute termination 4

Wide-QRS tachycardia (QRS ≥0.12 seconds):

• Assume ventricular tachycardia until proven otherwise 4
• Never use verapamil or diltiazem (may cause hemodynamic collapse) 4, 2
• Procainamide 20-50 mg/min IV or amiodarone 150 mg IV over 10 minutes 4
• Immediate cardioversion if hemodynamically unstable 4

Special Populations Requiring Modified Approach

Patients with angina or coronary artery disease:

• Beta-blockers are strongly preferred (reduce ischemia and mortality post-MI) 3, 6
• Avoid Class IC drugs entirely 4

Patients with hypertension:

• Beta-blockers provide dual benefit for rate control and blood pressure management 1
• Alternative: diltiazem or verapamil if beta-blockers contraindicated 4

Patients with heart failure (LVEF <40%):

• Beta-blockers remain first-line (mortality benefit) 2
• Avoid diltiazem and verapamil (negative inotropic effects) 4, 2
• Digoxin 0.125-0.25 mg daily may be added for rate control 4

Patients with asthma/COPD:

• Use cardioselective beta-blockers cautiously (metoprolol, atenolol, bisoprolol) 2
• Alternative: diltiazem or verapamil 4
• Avoid propranolol and carvedilol (non-selective beta-blockade) 2

Common Pitfalls to Avoid

• Do not use digoxin or amiodarone for acute narrow-QRS tachycardia (no longer recommended) 4
• Do not combine IV beta-blockers with IV calcium channel blockers (risk of severe bradycardia and hypotension) 4
• Do not use adenosine in patients with severe asthma (may precipitate bronchospasm) 4
• Do not assume wide-QRS tachycardia is supraventricular (most are ventricular in origin) 4
• Do not use Class IC drugs in patients with any structural heart disease (increased mortality risk) 4