Increased lipoprotein(a) is associated with reduced myocardial vasoreactivity in young healthy men

Objectives and Background: We examined the association between lipoprotein(a) and myocardial vasoreactivity in healthy men. Methods: Thirty non-smoking healthy men (age 34 ± 6 years) were studied: 9 had increased lipoprotein(a) (>200 mg/L) concentrations (lipoprotein(a) 317 (range 218–550) mg/L) and 21 had normal lipoprotein(a) (<200 mg/L) concentrations (lipoprotein(a) 57 (range 13–156) mg/L). The myocardial blood flow measurements were performed basally and during adenosine infusion (140 μg/kg/min) with or without simultaneous physiological hyperinsulinemia (insulin infusion at a rate of 1 mU/kg/min) using positron emission tomography and [15O]H2O. Results: Basal myocardial blood flow was similar between the subjects with increased and normal lipoprotein(a) (0.76 ± 0.20 and 0.79 ± 0.20 mL g−1 min−1, NS). Adenosine-stimulated flow tended to be reduced in subjects with increased lipoprotein(a) (3.1 ± 0.7 mL g−1 min−1 versus 3.7 ± 1.1 mL g−1 min−1, respectively, p = 0.1). During physiological hyperinsulinemia adenosine-stimulated flow was further enhanced in both groups but significantly blunted in subjects with increased lipoprotein(a) (3.7 ± 0.8 mL g−1 min−1 versus 4.8 ± 1.4 mL g−1 min−1, respectively, p = 0.03). This difference remained significant after simultaneous controlling for BMI, HbA1c, LDL-cholesterol, HDL-cholesterol and blood pressure (p = 0.04). Conclusions: Already young healthy men with lipoprotein(a) concentrations greater than 200 mg/L are characterized by impaired myocardial vasoreactivity.