From the Guidelines
The diagnostic workup for tachycardia should begin with a 12-lead ECG to confirm tachycardia and identify the type, as recommended by the 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1.
Initial Evaluation
The initial evaluation of a patient with tachycardia should include:
- A thorough history and physical examination to identify potential underlying causes
- Vital signs, including blood pressure and oxygen saturation
- Basic diagnostic tests, such as:
- Complete blood count (CBC)
- Electrolytes (especially potassium and magnesium)
- Thyroid function tests (TSH, free T4)
- Cardiac enzymes (troponin, CK-MB) if cardiac ischemia is suspected
Additional Tests
Additional tests should be considered based on clinical suspicion, including:
- Echocardiogram to evaluate for structural heart disease, as recommended by the 2003 ACC/AHA/ESC guidelines for the management of patients with supraventricular arrhythmias 1
- Stress test for ischemia
- Holter monitor for intermittent arrhythmias
- Electrophysiology study for complex arrhythmias
Importance of ECG
The ECG is a crucial diagnostic tool in the evaluation of tachycardia, as it can provide immediate information about the heart rhythm and help identify the underlying cause of the tachycardia, as noted in the 2015 ACC/AHA/HRS guideline 1.
Tailoring the Workup
The diagnostic workup should be tailored to the patient's specific presentation, with additional tests ordered based on clinical suspicion, to ensure a comprehensive evaluation while avoiding unnecessary procedures.
From the Research
Diagnostic Workup for Tachycardia
The diagnostic workup for tachycardia involves several steps, including:
- Patient history and physical examination to identify underlying conditions and symptoms 2, 3, 4, 5, 6
- Electrocardiogram (ECG) to document the tachycardia and classify it according to regularity of the rhythm and QRS width 2, 3, 4, 5, 6
- Laboratory workup to rule out underlying conditions such as hypokalemia or digitalis toxicity 3, 5, 6
- Extended cardiac monitoring with a Holter monitor or event recorder to confirm the diagnosis in patients with intermittent symptoms 5, 6
Classification of Tachycardia
Tachycardia can be classified into different types, including:
- Supraventricular tachycardia (SVT), which includes atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia, and atrial tachycardia 5, 6
- Ventricular tachycardia, which can be distinguished from SVT by the presence of atrioventricular dissociation, captured and fusion beats, and certain QRS shapes and concordance on the ECG 2
- Wide-complex tachycardias, which can be either ventricular or supraventricular in origin and require careful evaluation to determine the underlying mechanism 2
Diagnostic Tools
Several diagnostic tools can be used to evaluate patients with tachycardia, including:
- 12-lead ECG to document the tachycardia and classify it according to regularity of the rhythm and QRS width 2, 4
- Holter monitor or event recorder to confirm the diagnosis in patients with intermittent symptoms 5, 6
- Transesophageal lead or changing the position of V1 to assess atrial activity in patients with wide-complex tachycardias 2
- Electrophysiologic study and catheter ablation for patients with recurrent, symptomatic paroxysmal SVT 5, 6