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6.1.2 Ongoing Management: Recommendations

IIb B-R 1.  Intravenous beta blockers, diltiazem, or verapamil might be considered for acute treatment in patients with orthodromic AVRT who have pre-excitation on their resting ECG and have not responded to other therapies.42,266,267,269

See Online Data Supplements 11 and 12. Intravenous beta blockers, diltiazem, and verapamil have a risk of enhancing conduction over the accessory pathway if the AVRT converts to AF during administration of the medication. Should the patient have a rapidly conducting manifest accessory pathway, further enhancing accessory-pathway conduction during AF by shortening the refractory period (digoxin) or decreasing BP and increasing catecholamines (diltiazem, beta blockers, verapamil) may place the patient at risk of AF degenerating into a malignant ventricular arrhythmia. The ability to promptly perform electrical cardioversion must be available should AF with rapid ventricular conduction occur. Before intravenous beta blockers, diltiazem, and verapamil were available, intravenous digoxin was commonly used for acute treatment of patients with orthodromic AVRT who had pre-excitation on their resting ECG270; this agent is rarely used now because other agents are available and digoxin may put patients at risk of ventricular fibrillation.271 III: Harm C-LD 1.  Intravenous digoxin, intravenous amiodarone, intravenous or oral beta blockers, diltiazem, and verapamil are potentially harmful for acute treatment in patients with pre-excited AF.269,271–275

See Online Data Supplements 11 and 12. Patients with pre-excited AF should not receive intravenous digoxin, intravenous amiodarone, or intravenous/oral beta blockers, diltiazem, or verapamil because these medications may enhance conduction over the accessory pathway, increase the ventricular rate, and increase the risk of provoking a life-threatening ventricular arrhythmia.269,271–275 Digoxin increases the ventricular rate by shortening refractoriness of the accessory pathway, whereas amiodarone, beta blockers, diltiazem, and verapamil may increase the ventricular rate as a result of druginduced hypotension with increased catecholamines. In addition, these medications may enhance conduction over the accessory pathway by slowing or blocking conduction through the AV node, preventing competitive concealed retrograde conduction into the accessory pathway.

Recommendations for Acute Treatment of Orthodromic AVRT (Continued) COR LOE Recommendations

Recommendations for Ongoing Management of Orthodromic AVRT COR LOE Recommendations

I B-NR 1.  Catheter ablation of the accessory pathway is recommended in patients with AVRT and/or pre-excited AF.103,254,276–282

See Online Data Supplements 11 and 12. Several large series support the use of catheter ablation of the accessory pathway as first-line therapy in patients who have had AF and/or AVRT. These series report a success rate of approximately 93% to 95% and a 3% risk of major complications when patients are followed up for 6 months to 8 years102,103,254,276–282 (Table 8). AF in younger patients is usually associated with the accessory pathway and is unlikely to occur after ablation; in contrast, older patients may have recurrence of AF from causes unrelated to the accessory pathway.283,284 Catheter ablation is also effective for treating PJRT (Table 3) by ablating the concealed accessory pathway with a success rate of approximately 90%.283,284 Catheter ablation of an atriofascicular (Mahaim) pathway is successful in preventing reentrant tachycardia in approximately 70% to 100% of patients.285,286

I C-LD 2.  Oral beta blockers, diltiazem, or verapamil are indicated for ongoing management of AVRT in patients without preexcitation on their resting ECG.46,287 See Online Data Supplements 11 and 12. Observational studies and clinical experience confirm that beta blockers, diltiazem, and verapamil are effective for preventing recurrent tachycardia in approximately 50% of patients without pre-excitation on their resting ECG (concealed accessory pathway) and are associated with a favorable side effect profile.46,287

IIa B-R 1.  Oral flecainide or propafenone is reasonable for ongoing management in patients without structural heart disease or ischemic heart disease who have AVRT and/or pre-excited AF and are not candidates for, or prefer not to undergo, catheter ablation.45,108,109,112,288

See Online Data Supplements 11 and 12. Flecainide and propafenone are beneficial for the treatment of AVRT by directly slowing or blocking conduction over the pathway. These drugs are effective in approximately 85% to 90% of patients, with 30% reporting an absence of tachycardia.45,108,109,112,288 Both drugs have a risk of proarrhythmia resulting in VT that is increased in patients with structural heart disease or ischemic heart disease; in such patients, these drugs are generally avoided. Side effects occur in up to 60% of patients, and approximately 20% discontinue the medications because of adverse effects.45,108,109,112,288

IIb B-R 1.  Oral dofetilide or sotalol may be reasonable for ongoing management in patients with AVRT and/or pre-excited AF who are not candidates for, or prefer not to undergo, catheter ablation.99,106

See Online Data Supplement 9. Unlike flecainide and propafenone, sotalol and dofetilide can be used in patients with structural heart disease or coronary artery disease.105 Given the potential for significant QT prolongation and torsades de pointes, inpatient monitoring with serial ECGs is generally performed when these agents are initiated.

IIb C-LD 2.  Oral amiodarone may be considered for ongoing management in patients with AVRT and/or pre-excited AF who are not candidates for, or prefer not to undergo, catheter ablation and in whom beta blockers, diltiazem, flecainide, propafenone, and verapamil are ineffective or contraindicated.289,290 See Online Data Supplements 11 and 12. Small observational studies support the use of amiodarone for preventing recurrent AVRT, but long-term efficacy has not been reported.289,290 Because of the important toxicity associated with long-term use of amiodarone, the drug is usually reserved for patients who are not candidates for catheter ablation and who have failed to respond to or have contraindications to other antiarrhythmic drugs.

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