What could be causing a 30-year-old male with a history of bone development and growth disorders, who recently stopped smoking, to experience palpitations with tachycardia (heart rate of 140-150 beats per minute) and a sore throat, in the absence of chest pain or shortness of breath?

Tachycardia with Palpitations and Sore Throat in a Young Adult

This patient most likely has sinus tachycardia secondary to an acute infection (pharyngitis), and your immediate priority is to identify and treat the underlying cause rather than the heart rate itself. 1

Immediate Assessment

Determine if the tachycardia is primary or secondary. At a heart rate of 140-150 bpm, the American Heart Association guidelines state that symptoms of instability are unlikely to be caused primarily by the tachycardia unless there is impaired ventricular function. 1 In this case, the combination of sore throat with tachycardia strongly suggests a physiologic response to infection rather than a primary arrhythmia. 1

Key Clinical Indicators Supporting Sinus Tachycardia:

• Sinus tachycardia accelerates and terminates gradually, not abruptly, and is triggered by stressors like infection, fever, dehydration, or recent smoking cessation. 2
• The absence of chest pain, shortness of breath, syncope, or presyncope makes a dangerous primary arrhythmia less likely. 2
• The concurrent sore throat points to infection as the physiologic stressor. 1

Diagnostic Approach

Obtain a 12-lead ECG immediately to confirm the rhythm is regular sinus tachycardia and exclude pre-excitation patterns, accessory pathways, or other concerning findings. 2 This is the single most important initial test.

Pattern Recognition on ECG:

• Regular rhythm with normal P-wave morphology that shows gradual rate changes confirms sinus tachycardia. 3
• Look for pre-excitation (delta waves) which would suggest Wolff-Parkinson-White syndrome and require immediate electrophysiology referral. 2
• Exclude atrial fibrillation (irregular rhythm), atrial flutter, or other supraventricular tachycardias. 1

Additional Immediate Evaluation:

• Check vital signs including temperature to assess for fever. 1
• Assess oxygenation with pulse oximetry, as hypoxemia is a common cause of tachycardia. 1
• Evaluate for dehydration (dry mucous membranes, poor skin turgor, orthostatic changes). 1, 2
• Examine the throat for exudates, erythema, or tonsillar enlargement. 1

Management Strategy

Do not attempt to "normalize" the heart rate to <100 bpm when it is a compensatory response. 1, 3 This is a critical pitfall—when cardiac function is poor or the patient is compensating for another condition, normalizing the heart rate can be detrimental. 1

Treatment of Underlying Cause:

• Treat the pharyngitis with appropriate antibiotics if bacterial (consider rapid strep test or throat culture). 1
• Provide hydration if the patient is volume depleted. 1
• Antipyretics for fever if present. 1
• Reassure the patient that palpitations from sinus tachycardia in this context are benign. 2

When to Worry About Primary Arrhythmia:

Refer immediately to cardiology or emergency department if:

• The ECG shows pre-excitation, wide complex tachycardia, or irregular narrow complex tachycardia. 2
• The patient develops syncope, presyncope, severe dyspnea, or chest pain. 2
• The rhythm is irregular or shows sudden onset/termination (suggests AVNRT, AVRT, or atrial fibrillation). 2
• Heart rate remains >150 bpm after treating the underlying infection. 1

Follow-Up Considerations

If palpitations persist after the infection resolves, consider:

• 24-48 hour Holter monitoring if symptoms occur daily. 2
• Event or loop recorder if symptoms occur less frequently (several times per week). 2
• Thyroid function tests to exclude hyperthyroidism as a non-cardiac cause. 2
• Echocardiography only if there is clinical suspicion of structural heart disease or if sustained arrhythmia is documented. 2

Special Consideration for Bone Development Disorders:

While the patient's history of bone development and growth disorders is noted, this is unlikely to be directly related to the current presentation unless there is an associated syndrome affecting the cardiovascular system. 1 However, if the patient has a known syndrome (e.g., Marfan syndrome, homocystinuria), ensure appropriate cardiac screening has been performed previously. 2

Common Pitfalls to Avoid

• Do not start antiarrhythmic medications without documented arrhythmia, as they carry significant proarrhythmic risk. 2
• Do not order comprehensive laboratory panels routinely—target testing based on clinical suspicion. 2
• Do not rely on automatic ECG interpretation—these systems are unreliable and commonly suggest incorrect diagnoses. 2
• Do not dismiss the recent smoking cessation—nicotine withdrawal can cause anxiety and palpitations, but this should resolve within days to weeks. 2

In summary: Treat the infection, confirm sinus tachycardia with ECG, provide reassurance, and monitor for resolution as the underlying condition improves. 1, 2