Coronary microvascular dysfunction in asymptomatic patients affected by systemic sclerosis - limited vs. diffuse form.

Background: This observational study was designed to evaluate the prevalence of coronary microvascular dysfunction (CMD) in asymptomatic patients affected by systemic sclerosis (SSc), stratifying the results according to the limited (lcSSc) and the diffuse (dcSSc) forms of the disease.
Methods and Results: We enrolled 19 consecutive asymptomatic patients with dcSSc (n=7) or lcSSc (n=12). In all subjects, coronary flow reserve (CFR) was assessed by measuring diastolic coronary flow velocities in the left anterior descending artery by pulsed wave Doppler at baseline and after dipyridamole infusion (0.84 mg·kg(-1)·6 min(-1)). Wall motion score index was evaluated at baseline and during stress. We enrolled 20 healthy subjects as controls. Mean CFR was 1.96±0.62 in patients and 2.69±0.47 in controls (P<0.001). Abnormal values of CFR (≤2) were significantly more prevalent in patients than in controls (10/19 vs. 0/20; P<0.001) and in the dcSSc subgroup than in the lcSSc subgroup (6/7 vs. 4/12; P=0.05). An inverse relationship between disease duration (from time of onset of Raynaud's phenomenon) and CFR value was observed in the lcSSc group (correlation coefficient -0.583; P=0.046). Neither patients nor controls had wall motion abnormalities during dipyridamole administration.
Conclusions: A blunted CFR, most likely because of CMD, is more frequent in patients affected by the dcSSc form in the early stages of the disease, whereas it seems to appear later in lcSSc.