Effect of long-term β-blockade on aortic root compliance in patients with Marfan syndrome

Background: This study was undertaken to assess the effect of long-term β-blockade on the aortic root stiffness index and distensibility in patients with Marfan syndrome. Methods: Aortic root stiffness index and distensibility were calculated according to the formulas of Stefanadis and Hirai, respectively, with 2-dimensional guided M-mode echocardiogram before and after an average of 26 months of atenolol administration. Results: Twenty- three asymptomatic patients were studied (11 men and 12 women, aged 31 ± 14.2 years). The follow-up was 4 ± 2.2 years. The dose of atenolol was individualized (mean 43.5 ± 21.6 mg/d). Heart rate decreased from 79 ± 9 beats/min to 64 ± 9 beats/min (P = .01), and systolic blood pressure decreased from 124 ± 13 mm Hg to 114 ± 2 mm Hg (P = .01). Distensibility increased from 1.85 ± 0.70 x 10^-6 cm²/dynes^-1 to 2.21 ± 0.76 x 10^-6 cm²/dynes^-1 (P = .02), and the stiffness index decreased from 9.68 ± 3.78 to 8.85 ± 3.15 (P = .2). Two groups of responses to treatment were identified. Compared with baseline values 15 (65%) patients who responded to treatment had increased distensibility and decreased stiffness index of the aortic root (P = .05). Eight patients (35%) who did not respond to treatment had no significant change. Body weight >91 kg and baseline end-diastolic aortic root diameter >40 mm were significantly associated with no response (P = .05). Two patients in the nonresponding group had echocardiographic progression of aortic insufficiency. Conclusions: There was a heterogeneous response in the aortic root elastic properties after long-term treatment with atenolol in asymptomatic patients with Marfan syndrome. Stiffness index and distensibility are more likely to respond when the baseline end-diastolic aortic root diameter is <40 mm.