Evaluation of Persistent Orthostatic Tachycardia

Initial Diagnostic Workup

The American Heart Association recommends obtaining a 12-lead ECG at rest to look for pre-excitation patterns, prolonged QT interval, or other baseline abnormalities that would require immediate cardiology referral 1, 2
Assessing for hemodynamic stability by checking for chest pain, shortness of breath, hypotension, altered mental status, or signs of heart failure is crucial 3, 1
Obtaining vital signs, including orthostatic measurements, is essential to measure heart rate and blood pressure supine, then after standing for 3, 5, and 10 minutes 4, 1

The American College of Cardiology recommends checking TSH levels to exclude hyperthyroidism, which commonly presents with persistent tachycardia 2
A complete blood count is necessary to identify anemia as a reversible cause 1, 2
A basic metabolic panel is required to assess for electrolyte abnormalities and dehydration 2
Considering a drug screen is important if medication-induced tachycardia is suspected 3

An echocardiogram is necessary to exclude structural heart disease, including cardiomyopathy, valvular abnormalities, and assess left ventricular function 1, 2
A 24-hour Holter monitor is essential to document heart rate patterns throughout the day, confirm persistent daytime tachycardia, and nocturnal normalization 4, 1

The upper limit of physiologic sinus tachycardia is approximately 220 minus the patient's age, according to the American Heart Association 3, 1
Identifying and treating the underlying cause of physiologic sinus tachycardia, such as fever, infection, dehydration, anemia, pain, anxiety, medications, or hyperthyroidism, is crucial 3, 2
No specific antiarrhythmic therapy is indicated for physiologic sinus tachycardia; treatment is directed at the underlying cause 3, 2
Inappropriate sinus tachycardia is diagnosed if the persistent resting heart rate is >100 bpm with a mean 24-hour rate >90 bpm, according to the American College of Cardiology 1
First-line treatment for inappropriate sinus tachycardia is beta-blockers, as recommended by the American Heart Association 4

Immediate referral is required for pre-excitation (WPW syndrome) on ECG, wide-complex tachycardia of unknown origin, syncope during tachycardia or with exercise, documented sustained SVT, and recurrent episodes of regular, paroxysmal palpitations with abrupt onset/termination, according to the American College of Cardiology 1, 2, 5

Normalizing heart rate in compensatory tachycardia can be detrimental, as cardiac output can be dependent on a rapid heart rate, according to the American Heart Association 3, 1
Assuming "just anxiety" without proper cardiac evaluation can lead to misdiagnosis, as SVT and anxiety present with nearly identical symptoms, as noted by the American College of Cardiology 2, 5
Using AV nodal blocking agents if pre-excitation is present on ECG can be dangerous in atrial fibrillation with WPW, according to the American Heart Association 5
Recognizing tachycardia-mediated cardiomyopathy risk is essential, as persistent tachycardia can cause reversible cardiomyopathy requiring careful long-term follow-up, as recommended by the American College of Cardiology 1