Abstract Body (Do not enter title and authors here): Background: High serotonin from neuroendocrine tumors (NETs) can result in carcinoid heart disease (CaHD) with severe valve dysfunction, often requiring valve replacement surgery. Lutetium-177 (Lu-177), a targeted radioactive isotope therapy, is increasingly utilized in the treatment of NETs; however, there is limited data on its impact on bioprosthetic heart valves (BHVs) in CaHD.
Methods: A retrospective review was conducted on all patients with stage IV metastatic NET who underwent BHV replacement at three tertiary centers in the United States. Patients were stratified by Lu-177 therapy, administered after valve replacement. A propensity matched cohort of CaHD patients with BHV who did not received Lu-177 was curated including age, sex, and baseline left ventricular ejection fraction. Serial transthoracic echocardiograms (TTEs) following surgery were evaluated for progression of BHV degeneration; rise in mean gradient or increase in grade of prosthetic/periprosthetic regurgitation (grade increase of ≥1 out of 5), from first TTE following surgery (TTE1) to most recent TTE (TTE2). Analysis was performed at the level of individual valves, recognizing that some patients had more than one valve implanted. To account for changes in Lu-177 exposure over time, we constructed a time-varying Cox proportional hazards model. Accounting for non-independence of multiple valves within the same patient, a clustered Cox model was fitted using robust standard errors. Mortality was compared between patients exposed to Lu-177 therapy and those not exposed.
Results: 184 patients were identified, mean age 60.4 ± 10.3 years, 53.3 % male. Of these, 16 patients had Lu-177 therapy, with 45 individual BHVs within this group. Patients in the control group had a total of 60 BHVs. Across a median of 2.09 years [0.77-5.01] between TTE1 and TTE2, BHVs exposed to Lu-177 therapy demonstrated an increased risk of BHV degeneration (HR=2.44, 95% CI 1.05–5.69, p=0.038), accounting for the time between TTE1 and administration of Lu-177 and the non-independence of multiple BHVs within the same patient. There was no significant difference in mortality between the two cohorts (p=0.440).
Conclusions: BHVs in patients with CaHD exposed to Lu-177 therapy demonstrated an increased risk of degeneration. These findings suggest an association between Lu-177 treatment and accelerated prosthetic valvular deterioration, warranting further investigation and close monitoring in this patient population.