A Direct Oral Anticoagulant-Refractory Unusually Large Thrombus Attached to the Implantable Cardioverter-Defibrillator in a Patient on Rivaroxaban: A Case Report

Implantable cardioverter-defibrillators (ICDs) are the established method for the primary prevention of cardiac arrest in patients at risk of sudden cardiac death due to life-threatening ventricular arrhythmias or in selected patients with heart failure with reduced ejection fraction. The transvenous ICD (TV-ICD) system has been the established therapy for several decades; however, the complication of intracardiac thrombi on transvenous leads is a known risk. We present a case of a 54-year-old gentleman with previously implanted TV-ICD for ischaemic cardiomyopathy, who presented to the outpatient department for a routine echocardiogram. The echocardiogram showed a large ICD-lead thrombus despite being compliant with his anticoagulation therapy of rivaroxaban. He denied any shortness of breath, chest pain, fever, or night sweats. His case was discussed at the multidisciplinary team meeting, and the outcome was to switch from rivaroxaban to warfarin and to repeat the echocardiogram in six months. He also underwent transoesophageal echocardiogram, confirming the presence of a large ICD thrombus, and stayed in hospital for 72 hours. This case underscores the significance of anticoagulation pharmacokinetics when managing ICD-lead thrombi and highlights the potentially catastrophic sequelae of thrombi in patients with implantable cardiac devices. The occurrence of large ICD or pacemaker thrombus in anticoagulated patients who remain compliant with therapy is less common, and the anticoagulation option should be carefully discussed. Pacing lead thrombosis is a recognised complication of implantable cardiac devices. The risk is lower in optimally anticoagulated patients, and the management of pacing lead thrombosis depends on the thrombus size. Patients with smaller thrombi are at lower risk of serious complications than those with larger thrombi. Patients with implanted cardiac devices should be considered for anticoagulation if clinically indicated. Patients with implanted cardiac devices already on anticoagulation pose a significant clinical challenge.