Managing SVT in Addisonian Crisis

Critical First Steps: Address Both Conditions Simultaneously

The American Heart Association recommends proceeding directly to synchronized cardioversion (50-100J initial energy for SVT) in hemodynamically unstable patients, which achieves 100% conversion in such cases 1, 2, 3

In hemodynamically unstable patients, the American College of Cardiology suggests not delaying for pharmacologic interventions when the patient shows signs of instability, and instead proceeding with synchronized cardioversion 2, 3
For hemodynamically stable patients, the American Heart Association recommends attempting modified Valsalva maneuver first (31-43% success rate) as a safe and quick method to avoid need for medications 2, 3
The administration of adenosine 12 mg IV rapid bolus is recommended, as it achieves 90-95% effectiveness for AVNRT and AVRT, with recent evidence showing a significantly higher conversion rate than 6 mg (54.2% vs 40.6%, p=0.03) 1, 2, 3
IV beta-blockers (metoprolol or esmolol) are preferred over calcium channel blockers in this setting, given the hemodynamic fragility of Addisonian crisis, according to the American College of Cardiology 1, 2

The American Heart Association advises against assuming the SVT is the primary problem, as the Addisonian crisis is driving the clinical picture, and the tachycardia may resolve once cortisol and volume are repleted is not cited, however, avoiding AV nodal blocking agents if any possibility of pre-excited atrial fibrillation is recommended, as adenosine, diltiazem, verapamil, or beta-blockers can precipitate ventricular fibrillation in this setting 2
Obtaining a 12-lead ECG during tachycardia is recommended to confirm regular SVT and exclude ventricular tachycardia or pre-excited AF before administering any AV nodal blockers, according to the American College of Cardiology 2, 3

Arranging cardiology follow-up for consideration of catheter ablation (94.3-98.5% single-procedure success rate) to prevent recurrence once the acute crisis resolves is recommended by the American College of Cardiology 3