Coronary microvascular dysfunction in systemic sclerosis: insights from PET-derived myocardial flow reserve

Area of Science:

• Cardiology
• Rheumatology
• Nuclear Medicine

Background:

• Cardiovascular death is a leading cause in systemic sclerosis (SSc).
• Coronary microvascular dysfunction (CMVD) is a key contributor to cardiovascular mortality in SSc.
• Positron emission tomography (PET)-derived myocardial blood flow (MBF) and flow reserve (MFR) are validated noninvasive tools for assessing CMVD.

Purpose of the Study:

• To investigate the prevalence of impaired MFR in SSc patients.
• To explore the association between MFR and vasodilator or immunomodulatory therapies in SSc.

Main Methods:

• Retrospective study of 67 SSc patients and 201 matched controls who underwent 82-Rubidium PET myocardial perfusion imaging (MPI).
• Patients were matched 3:1 with controls based on age, sex, BMI, and cardiovascular comorbidities.
• Abnormal MFR was defined as < 2.0.

Main Results:

• SSc patients exhibited higher resting MBF (p=0.01) and lower MFR (p=0.01) compared to controls.
• No significant difference in stress MBF was observed between SSc patients and controls (p=0.85).
• Mycophenolate mofetil (MMF) use was associated with lower odds of abnormal MFR (OR 0.09, p=0.017), while calcium-channel blockers (OR 7.77, p=0.008) and statins (OR 7.14, p=0.008) were associated with increased odds.

Conclusions:

• PET MPI demonstrates reduced MFR in SSc patients, indicating CMVD.
• Treatment associations, particularly with MMF, CCBs, and statins, require cautious interpretation due to the retrospective design.
• PET-derived MFR may serve as a noninvasive biomarker for vascular involvement in SSc, necessitating prospective validation.