Introduction: We describe 2 patients with right anteroseptal accessory
pathway (ASAP) who developed new cardiomyopathy due to worsening AV node
conduction which resulted in more pre-excitation and frequent
orthodromic reciprocating tachycardia (ORT). Methods and Results: Case
1: 48-year-old female with a history of normally functioning mechanical
mitral valve, CABG, and pre-exitation that worsened after her open heart
surgery. She presented with frequent palpitations with documented
supraventricular tachycardia (SVT) and found to have a new
cardiomyopathy with decrease in ejection fraction (EF) from 55% to 46%
with dyssynchrony. Electrophysiological study confirmed a right ASAP and
ORT. The pathway was successfully ablated from the antegrade approach
after careful mapping. After ablation and six month follow up
echocardiogram showed improvement of EF to 54% and the LV dyssynchrony
resolved. Case 2: 51-year-old male with a history of frequent SVT with a
recent unsuccessful ablations that resulted in worsening pre-exitation,
more frequent SVT and new cardiomyopathy (EF from 60% to 40%). He was
started on Amiodarone which resulted in significant sinus bradycardia,
and intermittent pre-excitation and first degree AV block with no
improvement in his ORT events. His Electrophysiology study confirmed
ASAP which was successfully ablated from the antegrade approach after
careful HIS mapping. After one month follow-up echocardiogram showed an
improved ejection fraction to 60%. Conclusion: New cardiomyopathy due
to dyssynchrony and symptomatic frequent ORT of right ASAP can develop
in the setting of new iatrogenic diminished AV node conduction.
Successful ablation will result in LV function recovery to baseline.