ULTRASOUND (US) EVALUATION OF BOWEL VASCULOPATHY IN SYSTEMIC SCLEROSIS (SSC)

Background: Gastrointestinal involvement is one of the most frequent features of SSc, affecting nearly 90% of patients, with a great impact on quality of life and morbidity. One of the key pathological factors of SSc bowel involvement is vasculopathy (1), although little is known about its pathophysiology and no treatments are currently available. Objectives: to assess with abdominal US the superior mesenteric artery (SMA) and the inferior mesenteric artery (IMA) vessel characteristics and blood flow in SSc, compared to healthy controls (HC). Methods: we performed fasting abdominal US in SSc patients fulfilling the ACR/ EULAR 2013 classification criteria and HC. Patients with a history of peripheral / coronary arterial disease were excluded. For both SMA and IMA, caliber (mm), Peak Systolic Velocity – PSV (cm/sec), Reverse Velocity – RV (cm/sec), End-Diastolic Velocity – EDV (cm/sec), Mean Velocity – mV (cm/sec), Blood-flow (cm/ sec), Resistive Index – RI and Pulsatility Index – PI were measured. Results: 28 SSc patients [25 females (89.3%), mean age 48.75 ± 12.39 years; 6 (22.22%) anti-centromere and 19 (70.37%) positive for anti-topoisomerase I antibodies] and 28 HC [18 females (64.3%), mean age 36.25 ± 12.08 years] were evaluated. In SSc, the SMA caliber was significantly smaller than in HC (5.75 ± 0.62 vs. 6.45 ± 0.60mm, p<0.0001), while IMA dimensions did not differ. The SMA study revealed SSc patients had a significant reduction of RV (7.25 ± 6.37 vs. 18.52 ± 6.16cm/sec, p<0.0001) and PI (3.33 ± 0.75 vs. 4.53 ± 1.03, p<0.0001) when compared to HC. In addition, in SSc the mV of SMA was significantly lower than in HC (38.03 ± 13.90 vs. 28.32 ±9.25cm/sec, p=0.0035), as well as the RI (0.88 ± 0.04 vs. 0.91 ± 0.03, p=0.0034); EDV was significantly increased (16.34 ± 7.03 vs. 12.64 ± 5.46cm/sec, p=0.0321). Similarly to SMA, also in IMA RV and PI were significantly lower that controls (RV: 2.69 ± 6.10 vs. 17.06 ± 5.75cm/ sec, p<0.0001; PI: 3.54 ± 0.95 vs. 6.08 ± 1.53, p<0.0001). Moreover SSc patients presented a significant reduction of PSV and RI of IMA (PSV: 72.27 ± 27.23 vs. 93.81 ± 25.73cm/sec, p=0.0084; RI: 0.88 ± 0.04 vs. 0.91 ± 0.03, p=0.0132) when compared to HC. Although the HC group was significantly younger than the SSc group (p=0.0003), all the results were confirmed after adjustment for age (Table 1). Conclusion: this preliminary study shows, for the first time, the presence of a significant reduction of RV, PI and RI in the intestinal arteries of SSc patients when compared to HC. These data show an increased stiffness of the gastrointestinal arterial wall, in agreement with the typical SSc vasculopathy. A larger cohort is needed to confirm the results and explore the possible relationship with other clinical features of the disease.