- Email: [email protected]
Dual antiplatelet therapy versus warfarin anticoagulation in patients undergoing catheter ablation of atrial fibrillation
Letters to the Editor [5] Valgimigli M, Campo G, Monti M, et al. Short- versus long-term duration of dualantiplatelet therapy after coronary stenting: a randomized multicenter trial. Circulation Apr 24 2012;125(16):2015–26. [6] Campo G, Tebaldi M, Vranckx P, et al. Short vs. long term duration of dual antiplatelet therapy in patients treated for in-stent restenosis. A PRODIGY trial substudy. J Am Coll Cardiol 2014;63(6):506–12.
345
[7] Valgimigli M, Tebaldi M, Borghesi M, et al. Two-year outcomes after first- or secondgeneration drug-eluting or bare-metal stent implantation in all-comer patients undergoing percutaneous coronary intervention: a pre-specified analysis from the PRODIGY study. JACC Cardiovasc Interv 2014;7(1):20–8.
0167-5273/$ – see front matter © 2014 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijcard.2014.03.028
Dual antiplatelet therapy versus warfarin anticoagulation in patients undergoing catheter ablation of atrial fibrillation☆ Zhiyu Ling a, Fengpeng Jia b, Yanping Xu a, Li Su a, Zengzhang Liu a, Huaan Du a, Xiaoyu Yang a, Xianbin Lan a, Peilin Xiao a, Weijie Chen a, Jinqi Fan a, Suxin Luo b, Yuehui Yin a,⁎, Saman Nazarian c a b c
Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing Cardiac Arrhythmias Therapeutic Service Center, Chongqing 400010, China Department of Cardiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China Department of Cardiology/Medicine, Johns Hopkins University, Baltimore, MD 21287, USA
a r t i c l e
i n f o
Article history: Received 6 January 2014 Accepted 9 March 2014 Available online 15 March 2014 Keywords: Antiplatelet Anticoagulants Atrial fibrillation Catheter ablation Stroke Complications
Radio frequency catheter ablation (RFCA) has become a standard treatment for patients with atrial fibrillation (AF) [1]. Anticoagulation in patients undergoing AF ablation is crucial to minimize the risk of thromboembolic complications. Although warfarin is effective in reducing stroke, its chronic use has many disadvantages including frequent international normalized ratio (INR)/prothrombin, attention to numerous dietary and medication interactions, and risk of serious bleeding including intracranial hemorrhage [2–4]. Novel oral anticoagulants provide a reasonable alternative; however, they cannot yet be reversed, are expensive, and not yet widely available. As a result, many patients prefer aspirin to warfarin and novel anticoagulants. In 2009, Bunch et al. [5] first reported that selected low-risk patients with CHADS2 scores of 0 or 1 can safely be discharged on aspirin alone following left atrial ablation procedures. Recently, Duytschaever et al. [6] also demonstrated that periprocedural anticoagulation with Low Molecular Weight Heparin (LMWH) together with aspirin is effective and safe for the prevention of thromboembolic events in low thromboembolic risk patients undergoing ablation for AF. Both studies were in patients with CHADS2 scores of 0 or 1. The safety and efficacy of dual antiplatelet compared warfarin with LMWH bridging for antic-
☆ Author contributions: ZL and YY provided the idea for the article and contributed to drafting and subsequent revisions. SN contributed to manuscript revisions. All other authors contributed to data collection and revisions. ZL and FJ are co-first authors for this paper. The authors take full responsibility for the content of the article. ⁎ Corresponding author. E-mail address: [email protected] (Y. Yin).
oagulation in the periprocedural period in consecutive patients are unknown. We enrolled 561 consecutive patients undergoing AF ablation without left atrial appendage (LAA) thrombus on transesophageal echocardiography (TEE) which was performed 24 h prior to ablation. The study was approved by the Institutional Review Board of Chongqing Medical University, and informed consent was obtained from each patient and the study protocol conforms to the ethical guidelines of the 1975 Declaration of Helsinki as reflected in a priori approval by the institution's human research committee. Of the 561 patients, 268 were unwilling to take warfarin and were therefore treated with aspirin and clopidogrel. The other 293 patients were treated with warfarin. In the Aspirin plus clopidogrel group: Patients were administered with aspirin (75 mg/day) and clopidogrel (75 mg/day) 1 week before RFCA and uninterrupted throughout the periprocedural period and the following 3 months after RFCA. Low Molecular Weight Heparin (LMWH) was subcutaneously administered (4000 IU q12 h for enoxaparin or 4100 IU q12 h for nadroparin) 5 days before RFCA and continued until 12 h before the procedure. LMWH was resumed with the same dose after access sheath removal and stopped 7 days after RFCA. In the Warfarin group: Patients were administered with warfarin 3 weeks before the procedure with a therapeutic INR goal of 2.0–3.0. Warfarin was discontinued 3 days before the ablation procedure; “bridging” LMWH was used with the above-mentioned dosage and stopped 12 h before the ablation. After ablation, LMWH was resumed along with warfarin until a therapeutic INR was achieved. During the procedure, unfractionated heparin was administered in all patients as both a bolus and a continuous infusion after the transseptal puncture to maintain an activated clotting time (ACT) of 300–350 s. The double transseptal puncture was performed in all patients and the sheaths were continuously flushed with heparinized saline. All patients received neurological examination at the end of the procedure, 4 h after ablation and every day before discharge. All cerebral embolic events were evaluated with staged computed tomography (CT) or magnetic resonance imaging (MRI); the clinical diagnosis was further confirmed by the neurological specialists. The complications including thromboembolic and bleeding events were collected in this study. Outpatient follow-up was performed on day 15, and at 1, 2, and 3 months post procedure. In addition to detailed physical examination, Holter monitoring, routine blood tests and INR measurements were performed at each follow up. The dose of warfarin was adjusted to maintain a therapeutic INR in the warfarin group.
346
Letters to the Editor
Table 1 Baseline demographics of patients undergoing radio frequency catheter ablation for AF compared with anticoagulation strategy.
Table 2 Complications. Aspirin + clopidogrel Warfarin
Aspirin + clopidogrel Warfarin Characteristic
(N = 268)
(N = 293)
P
Age(yrs) Male gender, n (%) Hypertension, n (%) Diabetes mellitus, n (%) Congestive heart failure, n (%) Prior Stroke/TIA history, n (%) History of vascular disease, n (%) LV EF AF type Paroxysmal AF, n (%) Persistent AF, n (%) Long-standing persistent AF, n (%) LA dimension
56.9 ± 11.2 143(53.4%) 44(16.4%) 13(4.9%) 3(1.1)% 2(0.7%) 21(7.8%) 65.5 ± 6.1%
58.3 ± 11.5 164(56.0%) 71(24.2%) 21(7.2%) 5(1.7%) 4(1.4%) 14(4.8%) 65.0 ± 5.7%
0.784 0.553 0.028 0.290 0.727 0.688 0.162 0.327 0.647
221(82.1%) 44(16.4%) 4(1.5%) 35.2 ± 5.5 mm
CHA2DS2-VASc mean score 0, n (%) 1, n (%) 2, n (%) 3, n (%) 4, n (%) 5, n (%) HAS-BLED mean score 0, n (%) 1, n (%) 2, n (%) 3, n (%) Redo procedure
1.08 ± 0.96 78(29.1%) 123(45.9%) 40(14.9%) 22(8.2%) 5(1.9%) – 0.61 ± 0.66 130(48.5%) 112(41.8%) 26(9.7%) – 41(15.3%)
242(82.6%) 49(16.7%) 2(0.7%) 35.1 ± 5.3 mm 1.16 ± 0.98 76(25.9%) 126(43.0%) 66(22.5%) 19(6.5%) 4(1.4%) 2(0.7%) 0.69 ± 0.73 136(46.4%) 116(38.9%) 41(14.0%) 2(0.7%) 43(14.7%)
0.312 0.175
0.221
0.906
Values are n (%) or mean ± SD. TIA = transient ischemic attack; LVEF = left ventricular ejection fraction; AF = atrial fibrillation; LA = left atrium.
The baseline characteristics of patients have been summarized in Table 1. No significant differences were found between the 2 groups in terms of age, gender, diabetes, congestive heart failure, prior stroke/TIA history, vascular disease, left ventricular ejection fraction, left atrial dimension, pattern of AF and concomitant medications. There were no differences in mean CHA2DS2-VASc score and HAS-BLED Score between the aspirin plus clopidogrel and warfarin groups (1.08 ± 0.96 vs 1.16 ± 0.98, p = 0.175 and 0.61 ± 0.65 vs 0.69 ± 0.73, p = 0.185, respectively). Thromboembolic events occurred in two patients in each of the aspirin plus clopidogrel and warfarin groups during the procedure. In the warfarin group, a 65 years old male patient developed left eye hemianopia 30 min after the ablation; he recovered within 24 h without residual symptoms. Another 72-year old female patient developed left-sided muscle weakness post procedure. Both patients were treated conservatively with LMWH and warfarin until a therapeutic INR was achieved. No recurrent TIA or other thromboembolic event was noted in the following 3 months. Bleeding complications occurred in 30 (5.3%) patients. The incidence of major (3.0% vs 1.7%; p = 0.403) and minor bleeding complications (3.4% vs 2.7; p = 0.806) was similar between the aspirin plus clopidogrel and warfarin groups (Table 2). The requirement for monitoring of warfarin contributes to physician hesitation to recommend taking warfarin even to patients with higher risk of stroke. As a result many patients take aspirin and/ or clopidogrel instead of warfarin for the prevention of stroke in eastern countries [7–9]. Guo et al. [10] recently reported that there is no difference in stoke prevention between dual antiplatelet and oral
0167-5273/$ – see front matter © 2014 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijcard.2014.03.027
Total thromboembolic/bleeding events, n (%) Stroke, n (%) TIA, n (%) Total bleeding events, n (%) Major bleeding events, n (%) Minor bleeding events, n (%) Acute tamponade, n (%) Small pericardial effusion, n (%) Groin hematoma, n (%) Gastrointestinal bleeding, n (%) Other major bleeding events, n (%) Other minor bleeding events, n (%)
P
(N = 268)
(N = 293)
19(7.1%)
15(5.1%)
0.378
1(0.4%) 1(0.4%) 17(6.3%) 8(3.0%) 9(3.4%) 6(2.2%) 2(0.7%) 5(1.9%) 1(0.4%) 1(0.4%) 2(0.7%)
0(0%) 2(0.7%) 13(4.4%) 5(1.7%) 8(2.7%) 2(0.7%) 0(0%) 9(3.1%) 0(0%) 0(0%) 2(0.7%)
0.478 1.000 0.351 0.403 0.806 0.160 0.228 0.425 0.478 0.478 1.000
Values are n (%). TIA = transient ischemic attack.
anticoagulant strategies in patients with AF in China, perhaps reflecting an inappropriate INR range in clinical practice. In the present study, patients unwilling to take warfarin and referred for catheter ablation of AF, dual-antiplatelet and LMWH were used in the peri-procedural period. This peri-procedural antithrombotic strategy appears to be as effective and safe as an interrupted warfarin and heparin bridge strategy. In this prospective cohort study, the bleeding complications of AF ablation and 3-month risk of systemic thromboembolism post-ablation were similar in patients assigned to aspirin plus clopidogrel versus warfarin. These results suggest viability of a conservative anticoagulation strategy, and warrant confirmation in a randomized trial with long-term follow up. This work was supported by the Program for Innovative Research Team [NO. (2013)26] in the Second Affiliated Hospital, Chongqing Medical University.
References [1] Wann LS, Curtis AB, January CT, et al. ACCF/AHA/HRS:2011 ACCF/AHA/HRS focused update on the management of patients with atrial fibrillation (updating the 2006 guideline): a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2011;57:223–42. [2] Franco V, Polanczyk CA, Clausell N, et al. Role of dietary vitamin k intake in chronic oral anticoagulation: prospective evidence from observational and randomized protocols. Am J Med 2004;116:651–6. [3] Juurlink DN. Drug interactions with warfarin: what clinicians need to know. CMAJ 2007;177:369–71. [4] Hylek EM, Evans-Molina C, Shea C, et al. Major hemorrhage and tolerability of warfarin in the first year of therapy among elderly patients with atrial fibrillation. Circulation 2007;115:2689–96. [5] Bunch TJ, Crandall BG, Weiss JP, et al. Warfarin is not needed in low-risk patients following atrial fibrillation ablation procedures. J Cardiovasc Electrophysiol 2009;20:988–93. [6] Duytschaever M, Berte B, Acena M, et al. Catheter ablation of atrial fibrillation in patients at low thrombo-embolic risk: efficacy and safety of a simplified periprocedural anticoagulation strategy. J Cardiovasc Electrophysiol 2013;24:855–60. [7] Among stroke patients with atrial fibrillation in China: the China quest (quality evaluation of stroke care and treatment) registry study. Int J Stroke 2013;8:150–4. [8] Zhou Z, Hu D. An epidemiological study on the prevalence of atrial fibrillation in the chinese population of mainland china. J Epidemiol 2008;18:209–16. [9] Lip GY, Brechin CM, Lane DA. The global burden of atrial fibrillation and stroke: a systematic review of the epidemiology of atrial fibrillation in regions outside North America and Europe. Chest 2012;142:1489–98. [10] Guo Y, Pisters R, Apostolakis S, et al. Stroke risk and suboptimal thromboprophylaxis in chinese patients with atrial fibrillation: would the novel oral anticoagulants have an impact? Int J Cardiol 2013;168:515–22.
345
[7] Valgimigli M, Tebaldi M, Borghesi M, et al. Two-year outcomes after first- or secondgeneration drug-eluting or bare-metal stent implantation in all-comer patients undergoing percutaneous coronary intervention: a pre-specified analysis from the PRODIGY study. JACC Cardiovasc Interv 2014;7(1):20–8.
0167-5273/$ – see front matter © 2014 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijcard.2014.03.028
Dual antiplatelet therapy versus warfarin anticoagulation in patients undergoing catheter ablation of atrial fibrillation☆ Zhiyu Ling a, Fengpeng Jia b, Yanping Xu a, Li Su a, Zengzhang Liu a, Huaan Du a, Xiaoyu Yang a, Xianbin Lan a, Peilin Xiao a, Weijie Chen a, Jinqi Fan a, Suxin Luo b, Yuehui Yin a,⁎, Saman Nazarian c a b c
Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing Cardiac Arrhythmias Therapeutic Service Center, Chongqing 400010, China Department of Cardiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China Department of Cardiology/Medicine, Johns Hopkins University, Baltimore, MD 21287, USA
a r t i c l e
i n f o
Article history: Received 6 January 2014 Accepted 9 March 2014 Available online 15 March 2014 Keywords: Antiplatelet Anticoagulants Atrial fibrillation Catheter ablation Stroke Complications
Radio frequency catheter ablation (RFCA) has become a standard treatment for patients with atrial fibrillation (AF) [1]. Anticoagulation in patients undergoing AF ablation is crucial to minimize the risk of thromboembolic complications. Although warfarin is effective in reducing stroke, its chronic use has many disadvantages including frequent international normalized ratio (INR)/prothrombin, attention to numerous dietary and medication interactions, and risk of serious bleeding including intracranial hemorrhage [2–4]. Novel oral anticoagulants provide a reasonable alternative; however, they cannot yet be reversed, are expensive, and not yet widely available. As a result, many patients prefer aspirin to warfarin and novel anticoagulants. In 2009, Bunch et al. [5] first reported that selected low-risk patients with CHADS2 scores of 0 or 1 can safely be discharged on aspirin alone following left atrial ablation procedures. Recently, Duytschaever et al. [6] also demonstrated that periprocedural anticoagulation with Low Molecular Weight Heparin (LMWH) together with aspirin is effective and safe for the prevention of thromboembolic events in low thromboembolic risk patients undergoing ablation for AF. Both studies were in patients with CHADS2 scores of 0 or 1. The safety and efficacy of dual antiplatelet compared warfarin with LMWH bridging for antic-
☆ Author contributions: ZL and YY provided the idea for the article and contributed to drafting and subsequent revisions. SN contributed to manuscript revisions. All other authors contributed to data collection and revisions. ZL and FJ are co-first authors for this paper. The authors take full responsibility for the content of the article. ⁎ Corresponding author. E-mail address: [email protected] (Y. Yin).
oagulation in the periprocedural period in consecutive patients are unknown. We enrolled 561 consecutive patients undergoing AF ablation without left atrial appendage (LAA) thrombus on transesophageal echocardiography (TEE) which was performed 24 h prior to ablation. The study was approved by the Institutional Review Board of Chongqing Medical University, and informed consent was obtained from each patient and the study protocol conforms to the ethical guidelines of the 1975 Declaration of Helsinki as reflected in a priori approval by the institution's human research committee. Of the 561 patients, 268 were unwilling to take warfarin and were therefore treated with aspirin and clopidogrel. The other 293 patients were treated with warfarin. In the Aspirin plus clopidogrel group: Patients were administered with aspirin (75 mg/day) and clopidogrel (75 mg/day) 1 week before RFCA and uninterrupted throughout the periprocedural period and the following 3 months after RFCA. Low Molecular Weight Heparin (LMWH) was subcutaneously administered (4000 IU q12 h for enoxaparin or 4100 IU q12 h for nadroparin) 5 days before RFCA and continued until 12 h before the procedure. LMWH was resumed with the same dose after access sheath removal and stopped 7 days after RFCA. In the Warfarin group: Patients were administered with warfarin 3 weeks before the procedure with a therapeutic INR goal of 2.0–3.0. Warfarin was discontinued 3 days before the ablation procedure; “bridging” LMWH was used with the above-mentioned dosage and stopped 12 h before the ablation. After ablation, LMWH was resumed along with warfarin until a therapeutic INR was achieved. During the procedure, unfractionated heparin was administered in all patients as both a bolus and a continuous infusion after the transseptal puncture to maintain an activated clotting time (ACT) of 300–350 s. The double transseptal puncture was performed in all patients and the sheaths were continuously flushed with heparinized saline. All patients received neurological examination at the end of the procedure, 4 h after ablation and every day before discharge. All cerebral embolic events were evaluated with staged computed tomography (CT) or magnetic resonance imaging (MRI); the clinical diagnosis was further confirmed by the neurological specialists. The complications including thromboembolic and bleeding events were collected in this study. Outpatient follow-up was performed on day 15, and at 1, 2, and 3 months post procedure. In addition to detailed physical examination, Holter monitoring, routine blood tests and INR measurements were performed at each follow up. The dose of warfarin was adjusted to maintain a therapeutic INR in the warfarin group.
346
Letters to the Editor
Table 1 Baseline demographics of patients undergoing radio frequency catheter ablation for AF compared with anticoagulation strategy.
Table 2 Complications. Aspirin + clopidogrel Warfarin
Aspirin + clopidogrel Warfarin Characteristic
(N = 268)
(N = 293)
P
Age(yrs) Male gender, n (%) Hypertension, n (%) Diabetes mellitus, n (%) Congestive heart failure, n (%) Prior Stroke/TIA history, n (%) History of vascular disease, n (%) LV EF AF type Paroxysmal AF, n (%) Persistent AF, n (%) Long-standing persistent AF, n (%) LA dimension
56.9 ± 11.2 143(53.4%) 44(16.4%) 13(4.9%) 3(1.1)% 2(0.7%) 21(7.8%) 65.5 ± 6.1%
58.3 ± 11.5 164(56.0%) 71(24.2%) 21(7.2%) 5(1.7%) 4(1.4%) 14(4.8%) 65.0 ± 5.7%
0.784 0.553 0.028 0.290 0.727 0.688 0.162 0.327 0.647
221(82.1%) 44(16.4%) 4(1.5%) 35.2 ± 5.5 mm
CHA2DS2-VASc mean score 0, n (%) 1, n (%) 2, n (%) 3, n (%) 4, n (%) 5, n (%) HAS-BLED mean score 0, n (%) 1, n (%) 2, n (%) 3, n (%) Redo procedure
1.08 ± 0.96 78(29.1%) 123(45.9%) 40(14.9%) 22(8.2%) 5(1.9%) – 0.61 ± 0.66 130(48.5%) 112(41.8%) 26(9.7%) – 41(15.3%)
242(82.6%) 49(16.7%) 2(0.7%) 35.1 ± 5.3 mm 1.16 ± 0.98 76(25.9%) 126(43.0%) 66(22.5%) 19(6.5%) 4(1.4%) 2(0.7%) 0.69 ± 0.73 136(46.4%) 116(38.9%) 41(14.0%) 2(0.7%) 43(14.7%)
0.312 0.175
0.221
0.906
Values are n (%) or mean ± SD. TIA = transient ischemic attack; LVEF = left ventricular ejection fraction; AF = atrial fibrillation; LA = left atrium.
The baseline characteristics of patients have been summarized in Table 1. No significant differences were found between the 2 groups in terms of age, gender, diabetes, congestive heart failure, prior stroke/TIA history, vascular disease, left ventricular ejection fraction, left atrial dimension, pattern of AF and concomitant medications. There were no differences in mean CHA2DS2-VASc score and HAS-BLED Score between the aspirin plus clopidogrel and warfarin groups (1.08 ± 0.96 vs 1.16 ± 0.98, p = 0.175 and 0.61 ± 0.65 vs 0.69 ± 0.73, p = 0.185, respectively). Thromboembolic events occurred in two patients in each of the aspirin plus clopidogrel and warfarin groups during the procedure. In the warfarin group, a 65 years old male patient developed left eye hemianopia 30 min after the ablation; he recovered within 24 h without residual symptoms. Another 72-year old female patient developed left-sided muscle weakness post procedure. Both patients were treated conservatively with LMWH and warfarin until a therapeutic INR was achieved. No recurrent TIA or other thromboembolic event was noted in the following 3 months. Bleeding complications occurred in 30 (5.3%) patients. The incidence of major (3.0% vs 1.7%; p = 0.403) and minor bleeding complications (3.4% vs 2.7; p = 0.806) was similar between the aspirin plus clopidogrel and warfarin groups (Table 2). The requirement for monitoring of warfarin contributes to physician hesitation to recommend taking warfarin even to patients with higher risk of stroke. As a result many patients take aspirin and/ or clopidogrel instead of warfarin for the prevention of stroke in eastern countries [7–9]. Guo et al. [10] recently reported that there is no difference in stoke prevention between dual antiplatelet and oral
0167-5273/$ – see front matter © 2014 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijcard.2014.03.027
Total thromboembolic/bleeding events, n (%) Stroke, n (%) TIA, n (%) Total bleeding events, n (%) Major bleeding events, n (%) Minor bleeding events, n (%) Acute tamponade, n (%) Small pericardial effusion, n (%) Groin hematoma, n (%) Gastrointestinal bleeding, n (%) Other major bleeding events, n (%) Other minor bleeding events, n (%)
P
(N = 268)
(N = 293)
19(7.1%)
15(5.1%)
0.378
1(0.4%) 1(0.4%) 17(6.3%) 8(3.0%) 9(3.4%) 6(2.2%) 2(0.7%) 5(1.9%) 1(0.4%) 1(0.4%) 2(0.7%)
0(0%) 2(0.7%) 13(4.4%) 5(1.7%) 8(2.7%) 2(0.7%) 0(0%) 9(3.1%) 0(0%) 0(0%) 2(0.7%)
0.478 1.000 0.351 0.403 0.806 0.160 0.228 0.425 0.478 0.478 1.000
Values are n (%). TIA = transient ischemic attack.
anticoagulant strategies in patients with AF in China, perhaps reflecting an inappropriate INR range in clinical practice. In the present study, patients unwilling to take warfarin and referred for catheter ablation of AF, dual-antiplatelet and LMWH were used in the peri-procedural period. This peri-procedural antithrombotic strategy appears to be as effective and safe as an interrupted warfarin and heparin bridge strategy. In this prospective cohort study, the bleeding complications of AF ablation and 3-month risk of systemic thromboembolism post-ablation were similar in patients assigned to aspirin plus clopidogrel versus warfarin. These results suggest viability of a conservative anticoagulation strategy, and warrant confirmation in a randomized trial with long-term follow up. This work was supported by the Program for Innovative Research Team [NO. (2013)26] in the Second Affiliated Hospital, Chongqing Medical University.
References [1] Wann LS, Curtis AB, January CT, et al. ACCF/AHA/HRS:2011 ACCF/AHA/HRS focused update on the management of patients with atrial fibrillation (updating the 2006 guideline): a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2011;57:223–42. [2] Franco V, Polanczyk CA, Clausell N, et al. Role of dietary vitamin k intake in chronic oral anticoagulation: prospective evidence from observational and randomized protocols. Am J Med 2004;116:651–6. [3] Juurlink DN. Drug interactions with warfarin: what clinicians need to know. CMAJ 2007;177:369–71. [4] Hylek EM, Evans-Molina C, Shea C, et al. Major hemorrhage and tolerability of warfarin in the first year of therapy among elderly patients with atrial fibrillation. Circulation 2007;115:2689–96. [5] Bunch TJ, Crandall BG, Weiss JP, et al. Warfarin is not needed in low-risk patients following atrial fibrillation ablation procedures. J Cardiovasc Electrophysiol 2009;20:988–93. [6] Duytschaever M, Berte B, Acena M, et al. Catheter ablation of atrial fibrillation in patients at low thrombo-embolic risk: efficacy and safety of a simplified periprocedural anticoagulation strategy. J Cardiovasc Electrophysiol 2013;24:855–60. [7] Among stroke patients with atrial fibrillation in China: the China quest (quality evaluation of stroke care and treatment) registry study. Int J Stroke 2013;8:150–4. [8] Zhou Z, Hu D. An epidemiological study on the prevalence of atrial fibrillation in the chinese population of mainland china. J Epidemiol 2008;18:209–16. [9] Lip GY, Brechin CM, Lane DA. The global burden of atrial fibrillation and stroke: a systematic review of the epidemiology of atrial fibrillation in regions outside North America and Europe. Chest 2012;142:1489–98. [10] Guo Y, Pisters R, Apostolakis S, et al. Stroke risk and suboptimal thromboprophylaxis in chinese patients with atrial fibrillation: would the novel oral anticoagulants have an impact? Int J Cardiol 2013;168:515–22.