What is the best course of treatment for an adult or older adult patient with symptomatic arrhythmia, presenting with fluttering, dizziness, and near syncope, possibly with underlying cardiovascular disease?

Management of Symptomatic Arrhythmia with Fluttering, Dizziness, and Near Syncope

For an adult patient presenting with symptomatic arrhythmia characterized by fluttering, dizziness, and near syncope, immediate assessment of hemodynamic stability is mandatory, followed by 12-lead ECG to distinguish between supraventricular and ventricular arrhythmias, with unstable patients requiring immediate cardioversion and stable patients requiring urgent cardiology evaluation to prevent sudden cardiac death. 1

Immediate Assessment and Stabilization

Hemodynamic stability must be assessed within seconds of patient contact. 1, 2 Continuous ECG monitoring and intravenous access are mandatory for all patients presenting with any cardiac arrhythmia. 2, 3 The presence of near syncope indicates significant hemodynamic compromise and places this patient in a high-risk category requiring urgent intervention. 1

Unstable Patient Management

If the patient demonstrates any of the following, they are hemodynamically unstable and require immediate cardioversion: 1

• Ongoing syncope or loss of consciousness 1
• Persistent hypotension despite position changes 1
• Acute heart failure symptoms (pulmonary edema, severe dyspnea) 1
• Ongoing chest pain suggesting ischemia 1

For unstable supraventricular tachycardias, synchronized cardioversion should be performed at 50-100 J biphasic energy. 1, 3 For unstable ventricular arrhythmias, immediate cardioversion should be performed rather than attempting pharmacological termination. 1 After successful cardioversion, intravenous amiodarone should be initiated to prevent recurrence. 1, 3

Stable Patient Evaluation Algorithm

Step 1: Obtain 12-Lead ECG Immediately

The 12-lead ECG is the single most critical diagnostic tool and must be obtained during the arrhythmia if possible. 1, 4 This ECG should be evaluated for: 1

• QRS duration: Wide-complex (>120 ms) versus narrow-complex tachycardia 1
• Regularity: Regular versus irregular ventricular response 1
• Pre-excitation patterns (delta waves suggesting Wolff-Parkinson-White syndrome) 4
• AV dissociation or fusion complexes (diagnostic of ventricular tachycardia) 1
• QT interval prolongation (risk for torsades de pointes) 1

Step 2: Distinguish Arrhythmia Type

For narrow-complex regular tachycardia with near syncope: This likely represents AVNRT or AVRT. 1 Elderly patients with AVNRT are particularly prone to syncope or near-syncope despite slower tachycardia rates compared to younger patients. 1 The marked initial fall in systemic blood pressure occurs within the first 10-30 seconds of tachycardia onset, explaining the near-syncope symptoms. 1

For wide-complex tachycardia: Assume ventricular tachycardia until proven otherwise, especially in patients with structural heart disease. 1 The failure to correctly identify VT can be critical and potentially life-threatening. 1

For irregular tachycardia: Consider atrial fibrillation with rapid ventricular response, atrial flutter with variable conduction, or pre-excited atrial fibrillation. 1, 4

Acute Treatment Based on Rhythm

For Supraventricular Tachycardia (Stable)

1. Vagal maneuvers should be attempted first (Valsalva maneuver, carotid massage if no carotid bruits). 4

2. Adenosine 6-12 mg IV rapid bolus is the next step if vagal maneuvers fail. 1, 2, 3 Adenosine is relatively safe for both treatment and diagnosis of regular wide-complex tachycardia when the etiology is uncertain. 1 However, adenosine should NOT be used for irregular or polymorphic wide-complex tachycardia. 1

3. Beta-blockers, diltiazem, or verapamil are useful for rate control in hemodynamically tolerated SVT. 1 However, these AV nodal blocking agents are absolutely contraindicated in pre-excited atrial fibrillation or flutter, as they may accelerate the ventricular response and precipitate ventricular fibrillation. 1

4. Intravenous amiodarone may be more effective for rate control of atrial fibrillation or flutter and may restore sinus rhythm, particularly in patients with heart failure where other agents are contraindicated. 1

For Ventricular Tachycardia (Stable)

Amiodarone 150 mg IV over 10 minutes is the preferred agent for stable monomorphic ventricular tachycardia. 1 Amiodarone is generally well tolerated hemodynamically and is the safest antiarrhythmic agent, particularly in patients with structural heart disease. 1, 3

Critical Pitfalls to Avoid

Never use AV nodal blocking drugs (calcium channel blockers, beta-blockers, or digoxin) for pre-excited atrial fibrillation or flutter, as this can accelerate the ventricular rate and cause hemodynamic collapse. 1 If pre-excitation is suspected, amiodarone or procainamide are the appropriate choices. 1

Do not give serial AV nodal blocking agents with long half-lives (e.g., calcium channel blocker followed by beta-blocker), as profound bradycardia can develop from their overlapping effects. 1

Do not assume wide-complex tachycardia is SVT with aberrancy in patients with structural heart disease—treat as ventricular tachycardia until proven otherwise. 1

Mandatory Urgent Evaluation

All patients with near syncope associated with arrhythmia require: 1, 4

• Immediate cardiology or electrophysiology consultation 4
• Echocardiography to assess for structural heart disease, left ventricular function, and valvular abnormalities 1, 4
• Laboratory evaluation: TSH, electrolytes (particularly potassium and magnesium), complete blood count, and BNP 4
• Continuous cardiac monitoring with hospitalization 4, 2

High-Risk Features Requiring Hospitalization

The following features mandate hospital admission: 1, 4, 5

• Syncope or near-syncope with arrhythmia 1, 4
• Structural or ischemic heart disease 1
• Abnormal ECG findings (pre-excitation, prolonged QT, bundle branch block) 4
• Age >60 years with unexplained syncope 5
• Heart failure symptoms 1

Definitive Management Considerations

Catheter ablation is the definitive treatment for recurrent symptomatic SVT and should be considered after the acute episode is managed. 1, 4 For patients with Wolff-Parkinson-White syndrome, all require electrophysiology referral due to risk of sudden death, and catheter ablation is curative. 4

ICD implantation should be considered if ventricular arrhythmias are documented in patients with structural heart disease, particularly those with LVEF ≤35%. 1, 3

The prognosis depends entirely on the underlying cause: neurally-mediated syncope has a benign course, whereas cardiac syncope is associated with increased morbidity and mortality. 6, 5 Given this patient's symptoms of near syncope with arrhythmia, cardiac causes must be excluded before reassurance can be provided.