Pulmonary embolism (PE) is a relatively uncommon but serious complication of radiofrequency catheter ablation. Hockstad and Gornick reviewed six studies (5,652 patients) regarding PE as a complication of electrophysiologic procedures (including radiofrequency catheter ablation) and identified a PE complication rate between 0 and 1.7 percent.1 Although the incidence of PE is small, this complication has a greater than 15 percent mortality rate during the first three months following the diagnosis.2 Venous thromboembolism (VTE) is the most common preventable cause of in-hospital death.3 The use of VTE prophylaxis has been reported to reduce the incidence of deep venous thrombosis (DVT) and PE by 50 to 75 percent.3 A better understanding of PE risk factors and the proactive administration of thromboprophylaxis in high-risk patients may help minimize the risk of this complication.
A 53-year-old man with a history of minimal coronary artery disease, nonischemic cardiomyopathy, hypertension, diabetes, and a body mass index of 38.7, was recently treated at a different hospital for congestive heart failure. The previous hospital placed the patient on DVT prophylaxis and performed a computed tomography scan and a bilateral lower extremities venous ultrasound, which were negative for PE and DVT, respectively. Left and right cardiac catheterization procedures were performed, indicating a left ventricular ejection fraction of 10 percent. The patient was sent home with a wearable cardioverter defibrillator. He was admitted to Winthrop University Hospital for syncope and presyncope with rapid palpitations, and was placed on low-molecular-weight heparin, based on the use of the hospital’s VTE risk assessment tool and an elevated VTE risk profile. On the monitor, the patient had spontaneous supraventricular tachycardia (SVT) terminated by ventricular tachycardia (VT) and underwent a difficult two-and-a-half hour electrophysiology study/radiofrequency catheter ablation procedure, in which the two atrial tachycardias and atrial flutter were successfully ablated. Early the following day, the patient became hypotensive, tachycardic, tachypnic, and complained of chest tightness. A computed tomography of the chest was performed, which confirmed a diagnosis of a large PE in the right main pulmonary artery. The patient was placed on intravenous heparin and eventually converted to warfarin. He had a long run of VT with hemodynamic collapse and received an implantable cardioverter-defibrillator while therapeutic on warfarin therapy, and was subsequently discharged.
Various risk factors associated with VTE have been reported and include older age, obesity, immobility, hospitalization, malignancy, hypertension, congestive heart failure, and central venous catheterization.4,5 Some of these risk factors may be seen in Table 1. Despite these known risks, half of all patients with PEs have no obvious risk factors.4 The patient in this case report was clinically obese, had a history of hypertension and congestive heart failure, and underwent repeated catheterization of the femoral vein. Obese patients have been found to be two to three times more likely to get a VTE, and half of all inpatient mortalities following PE after an operation occur in obese patients.6
Venous catheterization is an essential component of most electrophysiology studies and radiofrequency catheter ablations. Hung and colleagues suggest that the use of multiple femoral sheaths during an electrophysiology study may increase the rate of DVT and subsequent PE by possibly causing venous stasis and/or injury to the vascular endothelium.9 More specifically, the rate of symptomatic PEs as a complication of electrophysiology procedures has been reported to be in the range of 0 to 1.7 percent.1 Although both electrophysiology procedures and catheter ablations utilize catheters, catheter ablations — as compared to electrophysiology studies — have a significantly higher overall rate of complications (3.1 percent vs. 1.1 percent, respectively).7
Anticoagulation is routinely administered during left-sided catheterization procedures in order to avoid a cerebrovascular thromboembolic event. Pure right-sided procedures do not typically include administration of systemic anticoagulants. In patients who may require a subsequent device implant, the institution of routine VTE prophylaxis, even in those at risk, is not entirely clear. In this case report, the patient was considered high risk for thrombosis. It is important to note in the above case that a PE occurred even though the patient received thromboprophylaxis with low-molecular-weight heparin.
One of the most significant risks during right-sided ablation is perforation, which may result in cardiac tamponade. Occasionally, the presentation of this serious condition may occur after the procedure (i.e., latent presentation). Typically, a PE can develop between 8.5 hours to 14 days after a catheter ablation.11 It is important to note that both PE and cardiac tamponade may occur after the procedure and may overlap with respect to the timing of their presentations. Therefore, it may be important to identify, and where appropriate and safe, consider the institution of VTE prophylaxis in especially high-risk patients following invasive cardiac procedures such as catheter ablation.
Studies have found that thromboprophylaxis decreases VTE incidence in surgical and medical inpatients by 50 to 75 percent.3 This case report emphasizes the point that VTE prophylaxis does not entirely eliminate PE risk but merely decreases the chance of its occurrence. VTE preventative measures may include: 1) early ambulation, 2) pharmacological thromboprophylaxis, and 3) intermittent pneumatic leg compression with sequential compression devices.3,12 The necessity of next day and/or staged device implantation following an electrophysiology study or radiofrequency catheter ablation may complicate the decision process, especially when considering pharmacological thromboprophylaxis. Sequential compression devices may provide a safe alternative in this instance without instituting additional anticoagulation prior to implantation of a pacemaker. Further research in this area would be beneficial in elucidating the benefits of this mechanical methodology.
Disclosure: The authors have no conflicts of interest to report regarding the article herein.
- Hockstad E, Gornick CC. Mildly symptomatic pulmonary emboli associated with electrophysiologic procedures. Indications for anticoagulant use. Chest.1994;106(6):1908-1911.
- Rajachandran M, Schainfeld RM. Medical and interventional options to treat pulmonary embolism. Curr Cardiol Rep. 2014;16(7):503.
- Wang TF, Wong CA, Milligan PE, Thoelke MS, Woeltje KF, Gage BF. Risk factors for inpatient venous thromboembolism despite thromboprophylaxis. Thromb Res.2014;133(1):25-29.
- Kroegel C, Reissig A. Principle mechanisms underlying venous thromboembolism: epidemiology, risk factors, pathophysiology and pathogenesis. Respiration.2003;70(1):7-30.
- Braunwald E, Bonow RO, Mann DL, Zipes DP, Libby P. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia: Saunders/Elsevier, 2011.
- Wang TF, Milligan PE, Wong CA, Deal EN, Thoelke MS, Gage BF. Efficacy and safety of high-dose thromboprophylaxis in morbidly obese inpatients. Thromb Haemost.2014;111(1):88-93.
- Chen SA, Chiang CE, Tai CT, et al. Complications of diagnostic electrophysiologic studies and radiofrequency catheter ablation in patients with tachyarrhythmias: an eight year survey of 3,966 consecutive procedures in a tertiary referral center. Am J Cardiol.1996;77:41e6.
- Anfinsen OG, Gjesdal K, Aass H, Brosstad F, Orning OM, Amlie JP. When should heparin preferably be administered during radiofrequency catheter ablation? Pacing Clin Electrophysiol. 2001;24(1):5-12.
- Hung CY, Lin TC, Hsieh YC, et al. Acute massive pulmonary embolism after radiofrequency catheter ablation: a rare complication after a common procedure. J Chin Med Assoc. 2012;75(8):409-412.
- Cappato R, Calkins H, Chen SA, et al. Delayed cardiac tamponade after radiofrequency catheter ablation of atrial fibrillation: a worldwide report. J Am Coll Cardiol.2011;58(25):2696-2697.
- Calkins H, Yong P, Miller JM, et al. Catheter ablation of accessory pathways, atrio-ventricular nodal reentrant tachycardia, and the atrioventricular junction: final results of a prospective, multicenter clinical trial. The Atakr Multicenter Investigators Group.Circulation. 1999;99(2):262-270.
- Kakkos SK, Caprini JA, Geroulakos G, Nicolaides AN, Stansby GP, Reddy DJ. Combined intermittent pneumatic leg compression and pharmacological prophylaxis for prevention of venous thromboembolism in high-risk patients. Cochrane Database Syst Rev. 2008;(4):CD005258.