Tc-99m sestamibi lower extremity muscle scan, is it a useful screening tool for assessment of preclinical atherosclerosis in rheumatoid arthritis patients?

Increased cardiovascular morbidity and mortality in rheumatoid arthritis (RA) patients cannot be entirely explained by traditional risk factors, suggesting that systemic inflammation characterizing this disease may accelerate atherosclerosis. Technetium 99m-Methoxyisobutyl isonitrile (Tc-99m sestamibi) is a myocardial perfusion imaging agent that has been suggested for evaluation of peripheral vascular disease. We used Tc-99m sestamibi muscle scan to investigate the prevalence of preclinical atherosclerosis in RA patients by perfusion reserve (PR) measurement. This study included 25 RA patients and 25 controls; 13/25 RA (GII) were on glucocorticoids and 12/25 (GI) were not. Database included full history, clinical examination, relevant laboratory tests, and Tc-99m sestamibi muscle scan for lower limbs. The percentage increase in the total counts (Cts) in the exercising calf termed PR was calculated according to the formula: (PR %) = (Cts in exercising calf-Cts in resting calf) ÷ (Cts in resting calf) × 100%. A significant difference was found between the means of PR in RA and controls (30.7±22.6% vs. 48.3±27.2%, P = 0.015). The mean perfusion reserve of GII correlated significantly with the steroids cumulative dose (P = 0.01). A statistically significant negative correlation was elicited between PR and disease duration (P = 0.024), while the negative correlation between PR and Disease Activity Index (DAS28) was not statistically significant (P = 0.065). Tc-99m sestamibi lower-limb muscle scan could be a useful screening tool for detection of preclinical atherosclerosis in lower limbs of RA patients, so early prophylactic measures and therapy modifications could be considered.