What is the treatment for inappropriate tachycardia?

Treatment of Inappropriate Sinus Tachycardia

Beta blockers should be prescribed as first-line therapy for inappropriate sinus tachycardia, with non-dihydropyridine calcium channel blockers as an alternative when beta blockers are contraindicated or ineffective. 1, 2

Diagnosis and Identification

Before initiating treatment, it's essential to confirm inappropriate sinus tachycardia (IST) using these criteria:

• Persistent sinus tachycardia (heart rate >100 bpm) at rest
• Excessive rate increase with minimal activity
• Nonparoxysmal nature (not abrupt onset/offset)
• P-wave morphology identical to sinus rhythm
• 24-hour Holter confirming elevated daytime rates with nocturnal normalization
• Exclusion of secondary causes (hyperthyroidism, pheochromocytoma, anemia, physical deconditioning) 1

Treatment Algorithm

First-line Treatment:

• Beta blockers (e.g., metoprolol 25-50 mg twice daily)
  • Mechanism: Reduces sympathetic tone on sinus node
  • Target: Resting heart rate between 60-80 bpm 1, 2
  • Caution: Avoid in severe bradycardia, high-degree AV block, decompensated heart failure, or severe reactive airway disease 2

Second-line Treatment (if beta blockers are ineffective or contraindicated):

• Non-dihydropyridine calcium channel blockers (verapamil or diltiazem)
  • Mechanism: Reduces calcium influx into sinus node cells
  • Caution: Do not combine with beta blockers due to risk of profound bradycardia 1, 2

Refractory Cases:

• Ivabradine (starting at 2.5-5 mg twice daily)
  • Mechanism: Selective inhibition of the sinus node "funny" current
  • Advantage: Heart rate reduction without affecting blood pressure 3, 4
  • Evidence suggests combining ivabradine with metoprolol may be effective in refractory cases 3

Last Resort (for highly symptomatic, treatment-refractory cases):

• Sinus node modification by catheter ablation
  • Acute success rate: 76%
  • Long-term success rate: approximately 66%
  • Potential complications: pericarditis, phrenic nerve injury, SVC syndrome, need for permanent pacing 1
  • Important: Exclude Postural Orthostatic Tachycardia Syndrome (POTS) before considering ablation 1

Special Considerations

• IST is predominantly seen in females (90%) with mean age of presentation around 38 years 1
• Treatment is primarily symptom-driven; the risk of tachycardia-induced cardiomyopathy is likely small 1
• Despite distressing symptoms, IST has not been associated with increased major cardiovascular events 5
• Symptoms may include palpitations, chest pain, shortness of breath, dizziness, lightheadedness, and pre-syncope 1

Common Pitfalls to Avoid

1. Misdiagnosis: Ensure proper differentiation from other supraventricular tachycardias that may mimic IST 6
2. Overtreatment: Since long-term outcomes are generally benign, avoid aggressive treatments unless symptoms are truly debilitating 7
3. Inadequate exclusion of secondary causes: Always rule out hyperthyroidism, anemia, dehydration, and other reversible causes before diagnosing IST 1
4. Failure to recognize POTS: Distinguish IST from Postural Orthostatic Tachycardia Syndrome, which requires different management 1, 2
5. Combining rate-controlling medications: Using beta blockers and calcium channel blockers together can cause profound bradycardia 2

By following this treatment approach, most patients with inappropriate sinus tachycardia can achieve symptomatic improvement and better quality of life.