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case_images: Electrocardiogram. (A) Atrial fibrillation rhythm with low ventricular response, 40 b.p.m. (B) Migratory atrial rhythm after electrical cardioversion.
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case_images: Electrocardiography showed atrial fibrillation with a low ventricular response, along with T-wave abnormalities in Leads II, III, and aVF (Figure 1A). Transoesophageal echocardiography did not detect thrombi in the left atrial appendage. Two electrical cardioversions were attempted at 200 J each, resulting in temporary atrial pacing with nodal escape rhythm (Figure 1B).
case_images: Transthoracic echocardiogram. (A) Preserved left ventricular ejection fraction. (B) Left atrial strain of 16%. (C) Left ventricular strain of -18.8%.
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case_images: The left atrial strain was measured at 16% (Figure 2).
case_images: Holter. (A) First-degree atrioventricular block with a PR interval of 400 ms. (B) Second-degree Mobitz 2 atrioventricular block. (C) Third-degree atrioventricular block. (D) Sinus pause of 3.8 s with nodal escape.
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case_images: Holter monitoring revealed first-degree atrioventricular block with a PR interval of 400 ms, second-degree Mobitz 2 atrioventricular block, third-degree atrioventricular block, four sinus pauses, the longest being 3.8 s, and migratory atrial rhythm (Figure 3).
case_images: Exercise stress test. (A) Atrial fibrillation reaching up to 160 b.p.m. (B) Sinus rhythm during the recovery stage.
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case_images: Class I (Figure 4). Coronary computed tomography angiography showed no evidence of atherosclerotic disease, normal coronary artery origins with left dominance, a calcium score of 0 AU, and CAD-RADS of 0.
case_images: Follow-up after 30 days. (A) Electrocardiogram showing sinus rhythm with first-degree atrioventricular block (PR interval 320 ms). (B) Twenty-four-hour Holter monitoring demonstrating baseline sinus rhythm with first-degree atrioventricular block (PR interval 340 ms). (C) Minimum heart rate recorded at 39 b.p.m.
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case_images: Holter monitoring at 30 days revealed only first-degree atrioventricular block with a minimum heart rate of 39 b.p.m., and at 6 months, the patient presented with sinus rhythm and a resting heart rate of 58 b.p.m. on ECG (Figure 5).