Impact of pretransplant mitral annular calcification on the incidence of cardiac events after renal transplantation

Prognostic Value of Mitral Annular Calcification in Liver Transplant Patients: Implication in Posttransplant Outcomes

BACKGROUND

With the rise of metabolic diseases and aging in liver transplant (LT) candidates, mitral annular calcification (MAC) is more recognizable. Despite cardiovascular risk becoming a leading cause of mortality in LT recipients, the influence of MAC remains unexamined. This study investigates the prevalence, related factors, and impact of MAC on LT outcomes.

METHODS

We explored 4148 consecutive LT patients who underwent routine pretransplant echocardiography from 2008 to 2019. Multivariate logistic analysis and the tree-based Shapley additive explanation scores in machine learning were used to evaluate the significant and important related factors. The primary outcome was 30-d major adverse cardiac events (MACE), and the secondary outcome was a median of 5-y cumulative all-cause mortality.

RESULTS

MAC was found in 123 (3.0%) patients. Significant and important related factors included age, alcoholic liver disease, chronic kidney disease, hyperuricemia, hypertension, and coronary artery disease. The MACE rate was higher in patients with MAC compared with those without MAC at 30 d (P < 0.001, adjusted hazard ratio 1.67; 95% confidence interval, 1.08-2.57). Patients with MAC had poorer cumulative overall survival probability compared with those without MAC (P = 0.0016; adjusted hazard ratio 1.47; 95% confidence interval, 1.01-2.15). Specifically, women with MAC had a poorer survival probability compared with men without MAC (65.0% versus 80.7%, P < 0.001) >10 y post-LT.

CONCLUSIONS

The presence of MAC before LT was linked to increased 30-d MACE and lower long-term survival rates, especially in women. Identification and management of MAC and potential risk factors are crucial for improving post-LT survival.

Cardiac evaluation of the kidney or liver transplant candidate

PURPOSE OF REVIEW

As the field of transplant has advanced, cardiac events have become the leading cause of morbidity and mortality after liver and kidney transplantation ahead of graft failure and infection. This trend has been bolstered by the transplantation of older and sicker patients who have a higher burden of cardiovascular risk factors, accentuating the need to determine which patients should undergo more extensive cardiac evaluation prior to transplantation.

RECENT FINDINGS

Computed tomography coronary angiography with or without coronary artery calcium scoring is now preferred over stress imaging in most transplant candidates for assessment of coronary artery disease. Assessment of cardiac structure and function using transthoracic echocardiography with tissue doppler imaging and strain imaging is recommended, particularly in liver transplant candidates who are at high risk of cirrhotic cardiomyopathy, for which new diagnostic criteria were recently published in 2019.

SUMMARY

Cardiac evaluation of liver and kidney transplant candidates requires a global assessment for both short and long-term risk for cardiac events. Imaging of cardiac structure and function using transthoracic echocardiography with tissue doppler imaging and strain imaging is recommended. Risk stratification should consider both the anatomic and functional consequences of coronary artery disease in transplant candidates.

VIDEO ABSTRACT

http://links.lww.com/MOT/A27.

A Rat Model with Multivalve Calcification Induced by Subtotal Nephrectomy and High-Phosphorus Diet

Background

Chronic kidney disease (CKD) with known valve calcification (VC) places individuals at high risk of cardiovascular disease. The study of VC in CKD is challenging due to the lack of a suitable research model. Here, we established a rat model of multivalve calcification induced by subtotal nephrectomy and a high-phosphate (HP) diet and analyzed the valve characteristics.

Methods

We established a CKD model in Sprague-Dawley rats by performing 5/6 nephrectomy (5/6Nx) followed by feeding with chow containing different phosphate concentrations for 8, 12, or 16 weeks. The rats were divided into 4 groups: sham+normal phosphate (NP, 0.9% P), sham+high phosphate (HP, 2.0% P), 5/6Nx+NP, and 5/6Nx+HP. Serum creatinine (Scr), blood urea nitrogen (BUN), parathyroid hormone (PTH), calcium, phosphorus, and 24-h urine protein levels were investigated. Pathological examinations included histological characterization, safranin staining, Alcian blue staining, and von Kossa staining at different time points. Using nanoanalytical electron microscopy, we examined valves from rats in the 5/6Nx+HP and sham+HP groups and detected spherical particles using energy-dispersive spectroscopy (EDS) to observe microscopic changes in the valves. In addition, the calcified tissues were analyzed for phase and crystallization properties using an X-ray powder diffractometer.

Results

The rats in the 5/6Nx+HP and 5/6Nx+NP groups presented with increased levels of Scr, BUN, and 24-h urine protein compared with those of the rats in the sham+HP and sham+NP groups. High levels of PTH were observed, and hematoxylin and eosin staining and immunohistochemistry for proliferating cell nuclear antigen showed parathyroid hyperplasia in rats in the 5/6Nx+HP group but not in the 5/6Nx+NP group. In rats in the 5/6Nx+HP group, extracellular matrix glycosylation was observed in the aortic valve in the 12th week and the mitral valve in the 16th week. In the 16th week, chondrocytes appeared in the aortic valve, as confirmed by immunofluorescence and Western blotting. Calcified particles mainly composed of phosphorus and calcium were observed in both the aortic and mitral valves by transmission electron microscopy and scanning electron microscopy (SEM). The main mineral component of the calcified aortic valve particles was hydroxyapatite [Ca₅(PO₄)₃(OH)], as shown by X-ray diffraction. However, there were no obvious differences in heart function between rats in the 5/6Nx+HP and sham+HP groups.

Conclusions

Our findings demonstrate that multivalve calcification is involved in CKD following 16-week HP and that hydroxyapatite [Ca₅(PO₄)₃(OH)] is the main component of the calcified aortic valve particles of rats in the 5/6Nx+HP group.