Left ventricular involvement in right ventricular dysplasia/cardiomyopathy.

OBJECTIVE: To characterize pathological features of left ventricular (LV) involvement in right ventricular dysplasia/cardiomyopathy (RVD/C). DESIGN: Retrospective morphological case study. SETTING: Two referral-based university medical centres. MATERIALS: Seventeen hearts were studied: 15 from sudden cardiac deaths outside hospital and two explanted hearts, one removed for intractable arrhythmias and the other for right-sided heart failure. The subjects (three female) were aged 16 to 60 years. MAIN RESULTS: All had typical right ventricular features of RVD/C and morphological evidence of LV wall involvement, seven with microscopic changes only. Of 10 hearts with gross and microscopic lesions, nine had large or laminar segments involved. The LV free wall was affected in all cases and the ventricular septum (VS) in 15. Sixteen hearts were hypertrophied. In involved areas, the LV or VS walls were of 'normal' thickness or slightly thinned. Five histological patterns of involvement were recognized, of which four were found in the LV. More severe LV involvement was seen in the hearts of older patients. Complete transmural fatty replacement of the myocardium was not observed, nor were the LVs aneurysmal. Minimal or mild focal aggregates of inflammatory cells were seen in nine hearts and moderate inflammatory changes in two. Inflammation was usually associated with myocyte atrophy and only rarely with myonecrosis. CONCLUSIONS: This study suggests that patients with RVD/C who live long enough will likely have LV free wall involvement with frequent VS involvement. Pathologists may miss LV involvement on gross examination. It should be sought diligently in patients dying of the condition or receiving transplants for heart failure. Appropriate histological sections from both free wall and septum must be examined.