Background: Heart failure (HF) is highly prevalent worldwide and left ventricular assist devices (LVADs) have revolutionized the treatment of patient with advanced HF. With extended life expectancy, many potentially life-threatening long-term complications have been observed. One of them is outflow graft obstruction (OGO), which has different etiologies (e.g., intraluminal thrombosis, graft kinking, anastomotic stenosis, extrinsic compression). We here present detection principles and interventional treatment strategies of OGO caused by extrinsic compression of a largely acellular fibrinous material within the portion covered by the bend relief in patients on HeartMate 3 LVAD (Abbott, IL, USA).

Methods and Results: Between January 2015 and October 2022 405 consecutive patients underwent LVAD implantation at our institution. The incidence of OGO due to extrinsic compression was 2.0% (n=8). Median time to diagnosis of OGO after LVAD implantation was 1165 days (range 555-2294 days). Patient characteristics are summarized in Table 1. Patients showed different clinical symptoms, e.g. low flow of LVAD (n=4; 50%) and/or symptoms of HF. There was a standardized stepwise diagnostic algorithm, primary including basic lab parameters (LDH, NT-proBNP), LVAD log file analysis and echocardiography. In case of high suspicion of OGO gated cardiac CTA was performed (Figure 1). Having made the diagnosis of OGO all patients underwent angiography. During catheterization increased pressure gradient was confirmed. In all patients stenting of the outflow graft with uncovered balloon-expendables stents (GORE® Viabahn® VBX 11 x 79mm, AZ USA) was performed. To avoid the stenosis in the distal part of the outflow graft caused by migrated fibrinous material, stenting of the entire length of the outflow graft was required (Figure 2). No changes in antiplatelet and anticoagulation strategy were made.

The procedure was successful in all patients. Estimated LVAD flow increased by 28.6 % (mean increase 1.0 l/min). There was 0% in-hospital mortality and no interventional-related major adverse cardiac and cerebrovascular events (MACCE). Furthermore, no minor and major access-related complications such as bleeding, pseudoaneurysm, AV-fistula, embolism occurred during intervention. After a median follow-up of 192 days, no re-stenosis or stent migration was observed. One patient died 152 days after intervention due to COVID-19-related acute respiratory distress syndrome. No thromboembolic events were detected during follow-up.

Conclusions: OGO caused by extrinsic compression is a late complication after HM3 implantation. Stepwise diagnostic approach is required for proper diagnosis. Stent graft implantation for OGO is a feasible treatment option for these high-risk patients with very low complications rate in experienced centres making it a safe alternative to surgery.

Key words: advanced HF, LVAD, stenosis, stent