Intra-abdominal Vascular Calcification Measured by Calcium Scoring Correlates With Abnormal Pulse Pressure Measured by Ambulatory 24-Hour Blood Pressure Monitoring Among Kidney Transplant Recipients

Abstract

Vascular stiffness increases with advancing age and is a major risk factor for age-related morbidity and mortality. Calcium-induced vascular stiffness is a common pathologic process among patients with kidney disease. Vascular imaging can detect this condition but it lacks the quantification and scoring to correlate with the severity and the progression of the disease. It has been known that vascular calcification affects blood pressure by changing the elasticity of the major vessels, such as the abdominal aorta and the iliac arteries. This study aims to correlate the aortic and iliac arteries calcium deposits burden measured by calcium scoring with ambulatory 24-hour blood pressure measurements. A retrospective review of patients who underwent kidney transplantation at Mayo Clinic from January 2010 through December 2013 was performed. Patient demographics, risk factors, postoperative outcomes, calcium scoring and ambulatory 24-hour blood pressure measurements were collected. Eligible patients were defined as those who had a nonenhanced abdominal and pelvic computed tomography dated any time before or up to 1 year following the kidney transplant date. Calcium scores were calculated in the aorta, beginning just beneath the celiac artery, and extended through the common, internal, and external iliac arteries. Scoring ended at the origin of the inferior epigastric artery in the external iliac and sciatic notch in the internal iliac artery. The scores were analyzed parallel to the pulse pressure measured by ambulatory 24-hour blood pressure readings. Patients were divided into two groups: (1) normal pulse pressure (between 40 mm Hg and 60 mm Hg) and (2) abnormal pulse pressure (<40 mm Hg or >60 mm Hg). As shown in the Table, 102 patients were enrolled. Patients with abnormal pulse pressure were significantly younger than the patients with normal pulse pressure. Total calcium scoring of the aorta, common iliac, external iliac and internal iliac arteries was significantly higher and correlated with abnormal pulse pressure. A calcium scoring system could predict calcium vasculopathy among patient with kidney disease that correlate with their blood pressure measurements. The results of this study could impact the approach to diagnose and aggressively treat calcium related vascular stiffness among patients with kidney disease. Further research is required to discern if calcium scoring of the abdominal aorta and iliac arteries can be used as a possible imaging biomarker for specific clinical outcome stratification.TableDiastolic blood pressure (BP) in kidney transplant patients: Characteristics by pulse pressure groupPulse average <40 or >60(n = 42)Pulse average 40-60(n = 60)P valueAge at transplant.0002a No.4260 Mean (SD)59.3 (14.4)49.3 (13.4) Median60.545.0 Q1, Q354.0, 71.039.0, 59.5 Range(20.0-78.0)(23.0-78.0)Sex.7940b Female22 (52.4%)33 (55.0%) Male20 (47.6%)27 (45.0%)Systolic average.0007a No.4260 Mean (SD)136.1 (12.8)127.3 (10.0) Median133.5127.5 QJ128.0, 144.0120.5, 134.0 Range(105.0-162.0)(107.0-156.0)Diastolic average.0002a No.4260 Mean(SD)69.4 (8.5)76.7 (9.4) Median69.076.5 Q1, Q364.0. 76.071.5, 82.0 Range(54.0-95.0)(56.0-103.0)CA aortic artery.0050a No.4260 Mean (SD)3409.6 (4156.4)1797.0(3696.6) Median2114.2220.2 Q1, Q359.4, 580.80.0, 2200.3 Range(0.0-1521 8.l)(0.0-15434.2)CA common iliac.0022a No.4260 Mean (SD)1787.9 (2388.0)918.8 (1907.8) Median595.243.6 Q1, Q312.4, 2660.60.0, 868.5 Range(0.0-9464.5)(0.0-7732.9)CA external iliac.1386a No.4260 Mean (SD)225.3 (454.4)209.9(816.1) Median0.00.0 Q1, Q30.0, 121.60.0, 2.9 Range(0.0-1761.7)(0.0-6011.4)CA internal lilac.0008a No.4260 Mean (SD)1028.8 (1542.8)369.7(723.2) Median336.122.6 Q1, Q324.7, 1364.10.0, 320.4 Range(0.0-7251.2)(0.0-3322.3)Total CA.0013a N4260 Mean (SD)6451.5 (7445.8)3258.8 (6018.7) Median3642.6566.4 Q1, Q3676.7, 9384.20.0, 2942.2 Range(0.0-26889.0)(0.0-24344.0)CA, ; SD, standard deviation.aKruskal-Wallis test.bχ2 test. Open table in a new tab