What is the best course of action for a patient experiencing palpitations with tachycardia (heart rate of 105 beats per minute)?

Management of Palpitations with Heart Rate 105 bpm

For a patient with palpitations and heart rate of 105 bpm, focus on identifying and treating the underlying cause rather than the heart rate itself, as this rate is below the 150 bpm threshold where primary arrhythmias become likely and represents physiologic sinus tachycardia in most cases. 1, 2

Initial Assessment and Stabilization

Assess hemodynamic stability first - check for acute altered mental status, ischemic chest pain, acute heart failure, hypotension, or signs of shock. 1, 2 If any of these are present, proceed immediately to advanced cardiac life support protocols regardless of the heart rate. 1

Immediate Diagnostic Steps

• Evaluate oxygen saturation and respiratory status - look specifically for tachypnea, intercostal retractions, suprasternal retractions, or paradoxical abdominal breathing, as hypoxemia is a common reversible cause of tachycardia. 1, 2
• Attach cardiac monitor, obtain vital signs, and establish IV access. 1, 2
• Obtain a 12-lead ECG immediately to document rhythm, measure QRS duration, identify P-wave morphology and relationship to QRS, and look for pre-excitation (delta waves suggesting Wolff-Parkinson-White syndrome). 1, 3

Critical Decision Point: Rate-Based Risk Stratification

At 105 bpm, this tachycardia is most likely secondary to an underlying physiologic stress rather than a primary arrhythmia. 1, 2 The American Heart Association guidelines specify that ventricular rates below 150 bpm in the absence of ventricular dysfunction are more likely secondary to underlying conditions rather than the cause of instability. 1, 2

Exception: Lower Threshold for Workup

If the patient has known ventricular dysfunction, pursue aggressive workup even at rates below 150 bpm, as these patients are more vulnerable to rate-related hemodynamic compromise. 2

Identify and Treat Underlying Causes

Do not treat the heart rate directly with rate-controlling medications - therapy must be directed toward identification and treatment of the underlying cause. 1, 3 Common physiologic causes include:

• Fever, infection, dehydration, anemia, or pain - these are the most common causes in otherwise healthy patients. 3
• Hyperthyroidism - obtain TSH testing to exclude this diagnosis, as it commonly presents with persistent tachycardia. 3
• Anxiety or panic disorder - this is a critical diagnostic pitfall, as anxiety is frequently the actual diagnosis when SVT is suspected, but conversely, true SVT is frequently misdiagnosed as panic disorder. 3

Important Caveat About Compensatory Tachycardia

When cardiac function is poor, cardiac output can be dependent on a rapid heart rate. 1 In such compensatory tachycardias, stroke volume is limited, so "normalizing" the heart rate with medications can be detrimental and potentially precipitate cardiovascular collapse. 1

ECG Interpretation and Referral Criteria

Immediate Cardiology Referral Required For:

• Pre-excitation (WPW syndrome) on ECG - these patients are at risk for significant morbidity and possibly sudden death. 1, 3
• Wide-complex tachycardia of unknown origin. 1, 3
• Syncope during tachycardia or with exercise. 1, 3
• Documented sustained supraventricular tachycardia. 3

Pattern Recognition for Specific Arrhythmias

Episodes of regular paroxysmal palpitations with sudden onset and termination suggest AVRT or AVNRT (paroxysmal supraventricular tachycardia). 1 Termination by vagal maneuvers further supports a re-entrant tachycardia involving AV nodal tissue. 1

Outpatient Monitoring Strategy

If palpitations are infrequent and not accompanied by angina, heart failure, or syncope, use event or wearable loop recorders rather than 24-hour Holter monitoring. 1 Event recorders are more cost-effective for capturing intermittent arrhythmias. 1, 4

• For frequent episodes (several per week): 24-hour Holter monitoring may be appropriate. 1, 4
• For less frequent episodes: Event or wearable loop recorder is preferred. 1
• For rare symptoms (fewer than two episodes per month): Consider implantable loop recorder if symptoms are severe. 1

Additional Investigations

Obtain echocardiography to exclude structural heart disease, which cannot be reliably detected by physical examination or 12-lead ECG alone. 1 This is particularly important if sustained SVT is documented or if there are concerning symptoms like syncope or dyspnea during palpitations. 1