EKG Findings in AF
Why should we treat AF with rapid ventricular rate in a stable/asymptomatic patient?
A persistently elevated ventricular rate during AF (usually > 120 beats/min) for prolonged time periods may result in mitral regurgitation, eventually leading to a dilated ventricular cardiomyopathy (tachycardia-induced cardiomyopathy).
- Acute alcohol intoxication
- Myocardial Contusion
- Valvular Heart Disease
- Pulmonary Embolism
- Digoxin Toxicity
- Pre-excitation Syndromes (WPW)
Who needs immediate Electrical Cardioversion?
- Altered mental status
- Ischemic chest discomfort
- Acute heart failure
- AF with rates b/w 250-300 and bizarre QRS morphology (suggesting WPW syndrome)
- When medications fail in stable patients
When doing Synchronised DC Cardioversion,
- Start with higher energy gives a better success rate
- Consider anterior-posterior pad placement for biphasic defibrillators
- Time with patient’s respiratory cycle, shock during full expiration
Phenylephrine/Calcium premedication prior to Verapamil can be considered for any unstable patient.
- BB: Often the first line medication to treat AF in the absence of pre-excitation syndromes. Beta blockers should be the first drug of choice in patients with congestive heart failure or left ventricular dysfunction, post-operative AF, hypertension, thyrotoxicosis, and acute coronary syndromes. Use BB with caution in patients with hypotension or acutely decompensated heart failure.
- CCB: CCBs are another first-line medications for the treatment of acute AF. CCB are preferred over BB on COPDs. Diltiazem tends to be more popular than verapamil for acute rate control, as verapamil has more potent negative inotropic and vasodilator effects that may lead to hypotension.
- Digoxin: Digoxin has both negative chronotropic and positive inotropic effects, which is particularly useful in patients with congestive heart failure, but the onset of action may take few hours. It is especially useful in hypotensive patients. Digoxin has a synergistic effect with BB/CCB. Verapamil may increase the concentration of digoxin.
- Mg: Magnesium decreases conduction through the AV node but Mg use is most often recommended only as an adjunctive therapy. Magnesium may also promote conversion to sinus rhythm, with some studies showing 50% to 60% of patients converted to sinus rhythm.
Choosing a Rhythm Control Agent
For Preexcitation syndromes such as Wolff-Parkinson White syndrome, the use of AV nodal blocking agents such as beta blockers, calcium channel blockers, and digoxin may induce ventricular brillation and are contraindicated.
Procainamide slows conduction through the accessory pathway and prolong the refractory period in the bypass tract, and they can be safely used in patients in rapid AF with Wolff-Parkinson-White syndrome. Procainamide is safer than Amiodarone in WPW Syndrome.
- AF with WPW - Sync Cardioversion for stable/unstable, Procainamide for stable
- Acute Stable AF - Rate Control with BB/CCB/Dig/Mg and wait for spontaneous cardioversion or Rhythm control with Procainamide/Amio
- Acute Unstable AF - Sync Cardioversion with concurrent heparin, May try rate control first
- Chronic Stable AF - Rate control with BB/CCB/Digoxin/ Mg
- Chronic Unstable AF - Sync. Electrical Cardioversion with heparin (if not on oral anti-coags), or rate control with BB/CCB/Mg/Digoxin, Consider phenylephrine/Calcium to premedicate and administer verapamil/amiodarone drip.
- AF Refractory to Cardioversion - After failed shocks, try medications and then shock again or Use phenylephrine/Calcium to premedicate and administer verapamil/amiodarone drip.