Ludman et al. have reported the prevalence of coronary artery calcification in heart transplant recipients and examined risk factors for calcifi- cation[1]. The authors noted that in some patients calcification was present despite angiographically trivial disease. One possible explanation to consider is that in cardiac transplant recipients, the usual close correlation between coronary artery calcification
and atheroma may not hold true.
Specifically, denervation might result in calcification of the media of coronary vessels. Medial calcification cannot easily be distinguished from intimal calcification with electron beam CT scanning.
Autopsy studies of unselected patients show that coronary calcification is atherosclerosis-related and intimal and this is the basis for using the calcification score as a proxy foratheroma burden. However, calcification of the media in in peripheral vessels is commonin diabetic patients in whom it is closely related to autonomic neuropathy and there are case reports of medial calcification in coronary vessels of diabetic patients.
Lumbar sympathectomy can also result in medial calcification
of peripheral vessels. Thus given that the transplanted heart is denervated
it is at least possible that some of the calcification detected
by Ludman et al is medial.
H.M. COLHOUN
Circ 1994; 90: 1786–93.
Clinical Lecturer in
Epidemiology and Public Health,
University College,
London, U.K.
