What is the patency rate of the Left Internal Mammary Artery (LIMA) graft after Coronary Artery Bypass Grafting (CABG) in patients with Pseudoxanthoma Elasticum (PXE)?

From the Guidelines

Patients with pseudoxanthoma elasticum (PXE) undergoing coronary artery bypass grafting (CABG) should exercise caution when using the left internal mammary artery (LIMA) as a graft due to potential calcification and reduced patency, with a reported higher patency rate of LIMA grafts in general CABG populations, as seen in studies such as 1 and 1. The LIMA, typically the preferred conduit for CABG due to its excellent long-term patency rates, may be compromised in PXE patients because this genetic disorder causes progressive calcification and fragmentation of elastic fibers in blood vessels. Some key points to consider in CABG include:

• Harvesting the internal mammary artery using the skeletonization technique to reduce the risk of sternal wound complications, as suggested in 1.
• Using an endoscopic saphenous vein harvest technique in patients at risk of wound complications, also mentioned in 1.
• Avoiding the use of the radial artery in patients with chronic kidney disease and a high likelihood of rapid progression to hemodialysis, as stated in 1. For PXE patients requiring CABG, saphenous vein grafts or radial artery grafts may be preferable alternatives. Preoperative assessment should include thorough imaging of potential conduits to evaluate calcification extent. If LIMA must be used, careful intraoperative assessment of the vessel quality is essential, and more frequent post-operative monitoring of graft patency is recommended. The reduced LIMA patency in PXE patients stems from the disorder's fundamental pathophysiology involving mutations in the ABCC6 gene, which leads to abnormal mineralization of elastic tissues, particularly affecting medium and small arteries throughout the body, including coronary vessels and potential bypass conduits. According to the most recent guidelines, such as 1, the use of LIMA versus saphenous vein grafts (SVG) for grafting of the left anterior descending (LAD) artery is supported by observational studies, which show improved survival and reduced cardiac events with LIMA use. However, these studies were conducted in general CABG populations, and the applicability of these findings to PXE patients is uncertain due to the potential for calcification and reduced patency of the LIMA graft in this population. Therefore, a cautious approach is recommended when considering the use of LIMA grafts in PXE patients undergoing CABG, with careful evaluation of the potential risks and benefits, as well as consideration of alternative graft options, such as saphenous vein or radial artery grafts.

From the Research

Patency Rate of Left Internal Mammary Artery (LIMA) Graft

• The patency rate of the Left Internal Mammary Artery (LIMA) graft after Coronary Artery Bypass Grafting (CABG) in patients with Pseudoxanthoma Elasticum (PXE) is not directly stated in the provided studies.
• However, a study from 2004 2 presents a patient with PXE-related coronary artery disease who has had long-term patency of a LIMA graft after an off-pump CABG procedure.
• Another study from 2024 3 suggests that the left internal mammary artery can be used as a standard conduit in CABG for patients with PXE, but further studies are required to standardize the practice.

Suitability of Arterial Conduits in PXE Patients

• A study from 2004 2 mentions that the suitability of arterial conduits, including the internal mammary artery, has been controversial in patients with PXE-related coronary artery disease.
• However, the study from 2024 3 indicates that the predilection of histopathological changes in PXE patients should not prevent the routine use of the left internal mammary artery as a standard conduit in CABG.

General Patency Rates of LIMA Grafts

• A study from 2006 4 states that LIMA is accepted as the 'gold standard' for surgical revascularisation due to its better long-term patency rates and survival in patients undergoing CABG.
• Another study from 2020 5 reports a high success rate of LIMA grafts in patients with coronary artery disease, with a low rate of graft failure and postoperative myocardial infarction.

Limitations and Rare Cases

• A case report from 1994 6 mentions a patient with PXE who underwent CABG using saphenous vein grafts, as the left internal mammary artery was obstructed and could not be used.
• The study from 2024 3 presents a rare case of a patient with PXE who underwent successful off-pump LIMA to LAD, which is the first case in the UK and the second one in the literature managed with an off-pump strategy.