Abnormal lipid measures are associated with structural degeneration of bioprosthetic aortic valves, a single-center study found.
The ratio of oxidized low-density lipoprotein (OxLDL) to high-density lipoprotein (HDL) was the only independent predictor for the valve degeneration that occurred in 21% of patients by 8 years after aortic valve replacement (odds ratio [OR] 1.49, 95% CI 1.08-2.07 per 10 units), Patrick Mathieu, MD, of Canada’s Quebec Heart and Lung Institute, and colleagues reported online in Heart.
Furthermore, elevated OxLDL/HDL and PCSK9 (expression of which is induced by OxLDL) together were tied to an almost three-fold increase of structural valve degeneration risk (OR 2.93, 95% 1.02-9.29).
“The present data suggest that lipids including the OxLDL/HDL ratio can be used as predictor of structural valve degeneration,” Mathieu told MedPage Today.
His group noted that explanted degenerated bioprostheses have shown infiltration of prosthetic leaflets with various lipid species, including OxLDL.
“This study indicates that there is an association between lipids and structural valve degeneration, but we cannot assume a causal relationship from the present data,” Mathieu cautioned. “Whether a lipid lowering strategy may decrease the risk of structural valve degeneration is not yet demonstrated. Hence, lipid lowering drugs should be used according to the guidelines to reach recommended targets.”
“Structural valve degeneration is a limitation of all tissue valves. Structural valve degeneration is associated with redo surgical intervention and symptom recurrence,” according to Danny Dvir, MD, of St. Paul’s Hospital in Vancouver.
Dvir, who was not part of Mathieu’s investigation, told MedPage Today that “this is clearly an adverse event we need to prevent as much as we can,” suggesting that prevention may be possible “by identifying subgroups in which mechanical valves could be favoured and by applying a specific approach to those that were treated by a bioprosthetic valve.”
He had presented data recently at the EuroPCR meeting suggesting that many transcatheter aortic valve replacement bioprostheses degenerate within 10 years.
Mathieu and colleagues’ single-center study included 199 consecutive patients who underwent bioprosthetic aortic valve replacement and had subsequent Doppler echocardiographic evaluation and blood sampling.
Structural valve degeneration was defined as an increase in mean transprosthetic gradient over 10 mm Hg or a worsening of transprosthetic regurgitation over follow-up.
Nonsignificant trends with valve degeneration were seen for high levels of apolipoprotein B (OR 1.21, 95% CI 0.96-1.51), OxLDL (OR 1.30, 95% CI 0.98-1.72), and small, dense LDL (LDL<225A, OR 1.09, 95% CI 0.99-1.19).
Limitations of the study included its single-center, observational design. As such, “whether OxLDL and PCSK9 have predictive value in longitudinal studies remain to be determined,” the authors wrote.
“Follow-up was on average 8 years, which may not be long enough to reveal structural valve degeneration in many cases,” added Dvir. “However, the authors showed that several metabolic parameters, including the level of plasma LDL and apoB and, very significantly, the level of OxLDL/HDL ratio was independently associated with structural valve degeneration per study definition.”
Mathieu’s group also used a “a relatively soft” definition for structural valve degeneration, Dvir commented to MedPage Today.
“Dyslipidemia is long considered a correlate of native valvular stenosis,” he said. “Clinicians should view patients with dyslipidemia as having an increased risk for valvular degeneration.”
However, “We do not know yet whether dyslipidemia parameters increase the risk of structural valve degeneration using a more solid definition of severe valve degeneration/reintervention. This may require a much larger group of patients and a much longer follow up than in the current study.”
“Eventually, the most important evaluation would be to see whether intervention on metabolic parameters [by statins or others agents] can improve durability of implanted bioprosthetic valves. The fact that these interventions failed to change the course of disease in native aortic stenosis was disappointing,” he noted.
Mathieu disclosed no relevant conflicts of interest.
Dvir declared consulting for Edwards Lifesciences, Medtronic, and St. Jude Medical.
Nsaibia MJ, et al “Association between plasma lipoprotein levels and bioprosthetic valve structural degeneration” Heart 2016; DOI: 10.1136/heartjnl-2016-309541.