Europace Advance Access originally published online on November 6, 2008
Europace 2009 11(1):117-118; doi:10.1093/europace/eun300
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SHORT COMMUNICATIONS
Thrombo-embolic occlusion of the left anterior descending coronary artery complicating left atrial radiofrequency ablation
Division of Cardiology, University Hospital Basel, Petersgraben 4, 4031 Basel, Switzerland
* Corresponding author. Tel: +41 61 2655214; fax: +41 61 2654598. E-mail address: csticherling{at}uhbs.ch
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Abstract |
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Left atrial ablation has become common clinical practice for the treatment of paroxysmal atrial fibrillation. We report a case of thrombo-embolic occlusion of the left anterior descending coronary artery complicating left atrial radiofrequency ablation in a patient with factor V Leyden mutation and a prior episode of pulmonary embolism.
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Case report |
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We report the case of a 53-year-old patient suffering from a so far unreported complication of catheter-based radiofrequency ablation (RFA) for symptomatic paroxysmal atrial fibrillation (PAF).
His prior medical history was remarkable for known factor V Leyden mutation complicated by one episode of pulmonary embolism and a deep vein thrombosis in the left for which he was maintained on phenprocuomon. A transoesophageal echocardiography ruled out left atrial thrombi and confirmed the presence of a persistent foramen ovale (PFO).
Since no trans-septal puncture was anticipated, he was maintained on phenprocuomon with an international normalized ratio of 2.0 at the time of pulmonary vein isolation (PVI). During ablation of all pulmonary veins (PVs), intravenous heparin was added and the activated clotting time kept between 280 and 390 s. Two long, steerable sheaths (Aegilis, St Jude Medical Inc., Minnetonka, MN, USA) were intermittently forwarded to the left atrium to perform ablation with a 7 Fr Navistar Thermocool catheter (Biosense Webster, Diamond Bar, CA, USA) and to position the Lasso-catheter (Biosense Webster) in the PV ostia. Throughout the procedure, these sheaths were continuously flushed with saline at a rate of 50 mL/h. During RFA on the posterior atrial wall around the left and right superior PVs, marked bradycardia indicative of ablation of the ganglionic plexi was observed. The 12-lead ECG showed no signs of ischaemia at the time. The procedure went uneventful. The sheaths were pulled on the table and the patient received a pressure dressing for 8 h to stop groin bleeding. The 12-lead ECG performed on the ward after the procedure showed no signs of ischaemia, and the patient received 70 mg of enoxaparin subcutaneously twice daily starting from the evening of the procedure.
On the next morning, the ECG showed a loss of the R-wave along with markedly negative T-waves in leads V2–V4 (Figure 1) and an increase of the creatine kinase to 640 U/L (normal < 200 U/L) and of the troponin T levels to 2.98 µg/L (normal < 0.1 µg/L). The patient was asymptomatic and an echocardiography revealed a new akinetic segment in the antero-apical segment of the left ventricle. Coronary angiography showed a thrombus in the left anterior descending artery (LAD) and otherwise unremarkable coronary arteries (Figure 2). The thrombotic segment was dilated, and since there was no evidence for local plaques or dissection, no stent was implanted and the patient received abciximab for 12 h. The patient was discharged on marcoumar, aspirin, and clopidogrel for 4 weeks.
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Discussion |
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To the best of our knowledge, we present the first case of a thrombo-embolic occlusion of a coronary artery following catheter-based PVI for PAF. Several aspects of this case are noteworthy. First, the embolic complication occurred in the presence of full anticoagulation. The thrombus could have formed at the ablation sites in the left atrium, which appears unlikely since the patient was fully anticoagulated, and we performed only circular left atrial ablation omitting lines (25–30 W, saline irrigation of the Thermocool catheter with 20 mL/min, and total RFA duration: 2414 s). Another explanation could be that thrombi either formed in the long sheats or were shed from the catheters, when they were removed. We continuously flushed the two long sheats with 50 mL/h of saline. However, there is evidence that continuous high-flow perfusion of the sheats with up to 180 mL/h lowers the risk for thrombo-embolic complications when compared with low flow rates (3 mL/h).1
It cannot be excluded that our flow rate was too low. Theoretically, the clot could have also formed locally in the LAD. In the present case, this seems unlikely since the other vessels appeared to be completely smooth, and after dilatation the local segment was also unremarkable without the necessity for stent implantation. Finally, the pressure dressing to his right groin could have resulted in a period of prolonged venous stasis, resulting in thrombus formation leading to a crossed veno-arterial embolism through the PFO. Secondly, the patient experienced no pain during the LAD occlusion. During the procedure, he became markedly bradycardic during ablation around the ostia of the left and right superior PVs, indicating affection of the gangliotic plexi in this region. Since these plexi do also carry pain fibres, a temporary cardiac denervation is conceivable. The absence of pain may also be due to an only small myocardial infarction or to individual factors influencing pain perception.
Current literature states that a complication rate of around 6% has to be anticipated when performing the left atrial ablation procedures for atrial fibrillation. Thrombo-embolic complications occur in 1.1% of patients.2
Our observation suggests that the indication of PVI for the treatment of AF in patients at very high risk of thrombo-embolic events should be stringent and that serial ECG recordings after PVI in these patients should be carried out even in the absence of angina or other symptoms.
Conflict of interest: none declared.
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[1] Cauchemez B, Extramiana F, Chauchemez S, Cosson S, Zouzou H, Meddane M, et al. High-flow perfusion of sheaths for prevention of thromboembolic complications during complex catheter ablation in the left atrium. J Cardiovasc Electrophysiol (2004) 15:276–83.[Web of Science][Medline]
[2] Oral H, Chugh A, Ozaydin M, Good E, Fortino J, Sankaran S, et al. Risk of thromboembolic events after percutaneous left atrial radiofrequency ablation for atrial fibrillation. Circulation (2006) 114:759–65.
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