Lupus carditis: Evaluation with technetium-99m MIBI myocardial SPECT and heart rate variability

The objective of this paper was to investigate the incidence of myocardial perfusion defects in patients with systemic lupus erythematosus (SLE) assoc iated with dysautonomic alterations. Twenty patients without any sign or sy mptoms of heart disease, selected from a larger population of patients with SLE, underwent technetium-99m sestamibi (Tc-99m MIBI) single photon emissi on computed tomography (SPECT), at rest and after dipyridamole infusion; th ey also underwent heart rate variability (HRV) examination by a 24 hour amb ulatory electrocardiography, analyzing in the time domain the standard devi ation of the R-R intervals average (SDNN) and the percentage of R-R adjacen t intervals differing from each other more than 50 msec (pNN50); in the fre quency domain the low (LF) and high frequencies (HF) were analyzed. Twenty healthy volunteers served as control group for heart rate variability. At M IBI-SPECT examination, the scan was found abnormal in 15 patients and norma l in five: three patients demonstrated reversible defects in the anterosept al region, four had irreversible defects in a region (two in the anterosept al region and two in the lateral region), two had rest defects in two diffe rent regions (lateral and inferior, lateral and anteroseptal) that improved during dipyridamole scan, and six had both reversible and irreversible def ects: four in a single segment (three anteroseptal and one lateral, and two in two different regions, particularly anteroseptal and lateral, lateral a nd inferior). All 20 patients showed significantly lower HRV parameters in comparison with the control group, except for pNN50, which indicates decrea sed physiologic periodic fluctuations of the autonomic nervous system. In s ix patients who underwent coronary angiography, the epicardial vessels were found completely normal. In view of the high incidence of myocardial hypop erfusion in patients with HRV alterations, the authors hypothesize that aut onomic dysfunction may be associated with microvascular disease or metaboli c alteration. They also believe that MIBI scintigraphy is a suitable techni que in detecting myocardial damage in SLE patients free of clinical manifes tation.