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High maintenance rate of sinus rhythm after cardioversion in post-thyrotoxic chronic atrial fibrillation
Insights
Rhythm conversion is effective for post-thyrotoxic atrial fibrillation, even long-standing cases. Delayed cardioversion can improve success rates, with excellent maintenance of sinus rhythm observed.
Area of Science:
- Cardiology
- Endocrinology
Background:
- Atrial fibrillation (AF) is a common complication of thyrotoxicosis.
- Persistent AF in euthyroid patients post-thyrotoxicosis poses a challenge for rhythm conversion.
Purpose of the Study:
- To evaluate the efficacy and success rate of rhythm conversion in patients with post-thyrotoxic atrial fibrillation.
- To assess the long-term maintenance of sinus rhythm after successful cardioversion.
Main Methods:
- Rhythm conversion was attempted in 33 euthyroid patients with persistent post-thyrotoxic AF.
- Pharmacological conversion with disopyramide was the initial step, followed by electrical cardioversion for non-converters.
- Recurrence of thyrotoxicosis during the study period necessitated delayed cardioversion in some patients.
Main Results:
- Overall cardioversion success rate was 88% (29 out of 33 patients).
- Pharmacological conversion succeeded in 6 patients, while 19 required electrical cardioversion.
- Four patients who initially failed cardioversion due to recurrent thyrotoxicosis were successfully converted upon achieving euthyroid state, indicating delayed cardioversion's efficacy.
Conclusions:
- Cardioversion is recommended for thyrotoxic atrial fibrillation, irrespective of AF duration.
- Delayed cardioversion, particularly after achieving euthyroid state, can enhance success rates.
- Excellent long-term maintenance of sinus rhythm supports the encouragement of cardioversion in this patient group.
Abstract:
We performed rhythm conversion on 33 euthyroid patients with post-thyrotoxic atrial fibrillation who do not revert spontaneously to sinus rhythm from atrial fibrillation. The duration of atrial fibrillation ranged from 9 to 59 months (mean 25 +/- 14). The protocol of rhythm conversion was to first attempt pharmacological conversion with disopyramide and then to perform electrical cardioversion on the non-converters. Of 33 patients, 25 were converted to sinus rhythm (6 by disopyramide and 19 by electrical cardioversion), resulting in 8 non-converters. However, it was later discovered that cardioversion had been applied to 4 of the 8 non-converters when these patients had had a recurrence of thyrotoxicosis. These 4 patients were subjected to a second electrical cardioversion after attaining the euthyroid state. Sinus rhythm was restored in all 4 patients, giving a cardioversion rate of 88%. The sinus rhythm was maintained in 25 of the total 29 converters (86%) at the time of follow-up (10-68 months, mean 35 +/- 19 months). Our studies suggest that cardioversion should be encouraged for thyrotoxic atrial fibrillation, even if the duration of atrial fibrillation is long-standing, since there is excellent maintenance of sinus rhythm and even delayed application of cardioversion may improve its success rate.