Background/Purpose: Pulmonary hypertension (PH) is a major complication of systemic sclerosis (SSc). We observed that a significant proportion of our SSc patients with PH as diagnosed by right heart catheterization (RHC) had PH due to causes other than pulmonary arterial hypertension (PAH), notably left heart disease (LHD) (15/26, 58%). We hypothesized that LHD in these patients could be explained by cardiomyopathy secondary to microvascular disease and/or fibrosis. The aim of our study was to detect microvascular perfusion defects and/or fibrosis, as well as useful parameters for PH diagnosis, by cardiac magnetic resonance imaging (MRI) in SSc patients with and without PH.

Methods: A retrospective analysis of our cohort of 432 SSc patients was performed. All patients routinely underwent screening for PH, and diagnosis of PH was proven by RHC in all suspected cases. Data from clinical, cardiopulmonary and serological investigations were analyzed. All living patients with PH (n=18) as well as a control group of 19 consecutive SSc patients without clinical suspicion of PH underwent a cardiac MRI (a morphologic and functional study with steady state free precession technique in static and cine imaging, and a T2 short-term inversion recovery (STIR) study, followed by a delayed contrast-enhanced imaging acquisition).

Results: Twenty-six SSc patients (26/432; 6%) had PH diagnosed by RHC. Eighteen of these patients (11 with PH due to LHD [61%], 4 with PAH [22%], 3 from other causes) and 19 without clinical suspicion of PH (control group) underwent cardiac MRI. Age, disease duration, gender, ethnicity, disease subtypes and autoantibody profiles were similar between the two groups. Systolic pulmonary artery pressure by transthoracic echocardiography (48,3±7,5 mmHg vs 30,3±5,7 mmHg, p<0,001) as well as the carbon monoxide transfer factor (TLCO) (54,3±15,4% of predicted value vs 69,1±22,8% of predicted value, p=0,043) were statistically significantly different between SSc patients with and without PH, respectively. Cardiac MRI showed statistically significant differences between SSc patients with and without PH, respectively, for the measurement of the diameter of the main pulmonary artery (PA) (30,90±5,03 mm vs 26,30±3,86 mm, p=0,006), the right PA (23,50±4,11 vs 18,60±2,90 mm, p=0,001), and the ratio of the main PA to the ascending aorta (0,97±0,10 vs 0,84±0,10, p=0,002). There was a trend toward significance for the measurement of the left PA (21,60±3,52 mm vs 19,80±1,98 mm, p=0,07). None of the 37 patients had significant myocardial hypersignal in T2 STIR nor delayed gadolinium enhancement.

Conclusion: Cardiac MRI investigation did not show overt evidence of myocardial perfusion defects nor fibrosis to explain PH secondary to LHD in our SSc cohort. Newer more sensitive cardiac MRI modalities may be more useful and should be evaluated in future studies. However, cardiac MRI measurement of the diameter of the main PA, the right PA and possibly of the left PA, as well as the ratio of the main PA to the ascending aorta, seem to be simple and reliable methods for PH diagnosis in SSc patients, and may prove to be useful noninvasive tools in the investigation of PH.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/measurement-of-pulmonary-arteries-by-cardiac-magnetic-resonance-imaging-a-simple-and-useful-tool-for-the-detection-of-pulmonary-hypertension-in-systemic-sclerosis-patients-without-overt-cardiac-micro/