Features of left ventricular myocardial perfusion in patients with hypercholesterolemia

Abstract

Aim. To evaluate left ventricular myocardial perfusion patterns, assessed with single-photon emission computed tomography (SPECT), in asymptomatic patients with severe hypercholesterolemia (HCh).
Materials and Methods. The main group included 26 patients with total cholesterol level >7.5 mmol/l and/or high density lipoprotein cholesterol (LDL-cholesterol) >4.9 mmol/l, with no clinical signs of coronary artery disease. All patients, as well as 10 healthy volunteers, underwent myocardial ⁹⁹ᵐTc-MIBI (4.2-methoxy-isobutyl-isonitrile) rest/stress SPECT with CT (computer tomography) – attenuation correction. Standard quantitative perfusion parameters (rest/stress/reversibility extents, SRS, SSS, SDS) were evaluated. In addition, two new parameters for perfusion defects severity (σsev) or perfusion heterogeneity (σhet) assessment were calculated.
Results. Stress test results were negative in 73% of HCh patients. SPECT revealed no reliable reversible/irreversible perfusion defects, though inhomogeneous MIBI distribution was visually detected in 23 HCh patients (88%). Standard perfusion parameters showed no reliable difference between two groups: rest extent was 8.3 (5.0–11.0) and 7.3 (4.5–9.1), p>0.05; stress extent – 11.3 (6.5–14.0) and 6.3 (4.2–9.7), p>0.05; reversibility extent – 5.0 (2.5–8.0) and 5.5 (3.1–8.4), p>0.05; Summed Rest Score (SRS) – 3.5 (2.0–5.5) and 0.5 (0.0–1.5), p>0.05; Summed Stress Score (SSS) – 7.3 (4.5–9.5) and 4.8 (2.4–6.7), p>0.05; Summed Difference Score (SDS) – 2.5 (2.0–6.0) and 4.3 (0.5–6.5), p>0.05; while some σsev/σhet parameters were reliably higher in HCh patients: rest σsev – 25.4 (22.0–28.3) vs. 21.1 (18.2–23.2), p=0.06; rest σhet – 7.8 (6.9–8.7) vs. 4.7 (4.0–5.8), p=0.03; stress σhet – 8.2 (7.2–8.9) vs. 5,3 (3.4–6.7), p=0.03, respectively.
Conclusion. In patients with severe hypercholesterolemia initial myocardial perfusion impairments or inhomogeneous perfusion is often observed. However, standard perfusion parameters values show no reliable difference in those patients when compared to healthy volunteers. New σsev/σhet parameters are more suitable for assessment of initial myocardial perfusion impairments that are visually observed in HCh patients