Diffuse left ventricular interstitial fibrosis is associated with sub-clinical myocardial dysfunction in Alstrom Syndrome: an observational study

Background: Alstrom syndrome is a rare inherited ciliopathy with progressive multisystem involvement. Dilated cardiomyopathy is common in infancy and recurs or presents de novo in adults with high rates of premature cardiovascular death. Although Alstrom syndrome is characterised by fibrosis in solid organs such as the liver, the pathogenesis of related cardiomyopathy are not clear. To date it is not known whether diffuse interstitial myocardial fibrosis is present before the onset of heart failure symptoms or changes in conventional parameters of left ventricular function. Methods: In this observational study, 26 patients with Alstrom syndrome (mean age 27 +/- 9 years, 65 % male, 24 h ABPM 130 +/- 14 / 77 +/- 9 mmHg) without symptomatic cardiovascular disease were recruited from a single centre and compared to matched healthy controls. All subjects underwent cardiac MRI (1.5 T) to assess ventricular function, diffuse interstitial myocardial fibrosis by measurement of extracellular volume on T1-mapping (MOLLI) and coarse replacement fibrosis using standard late gadolinium enhancement imaging. Results: Global extracellular volume was increased in Alstrom syndrome with wider variation compared to controls (0.30 +/- 0.05 vs. 0.25 +/- 0.01, p < 0.05). Left ventricular long axis function and global longitudinal strain were impaired in Alstrom syndrome without change in ejection fraction, ventricular size or atrial stress (NT-proBNP) (p < 0.05). Global extracellular volume was associated with reduced peak systolic longitudinal strain (r = -0.73, p < 0.01) and strain rate (r = -0.57, p < 0.01), increased QTc interval (r = 0.49, p < 0.05) and serum triglycerides (r = 0.66, p < 0.01). Nine (35 %) patients had diffuse mid-wall late gadolinium enhancement in a non-coronary artery distribution. Conclusion: Diffuse interstitial myocardial fibrosis is common in Alstrom syndrome and is associated with impaired left ventricular systolic function. Serial studies are required to determine whether global extracellular volume may be an independent imaging biomarker of vulnerability to dilated cardiomyopathy and heart failure.