Association between glycated hemoglobin (HbA1c) level and cardiac perfusion and function on gated myocardial perfusion SPECT

Background Glycated hemoglobin (HbA1c) is a recognized biomarker that keeps track of long-term blood sugar levels. Some studies revealed that even a modest elevation of blood glucose levels was linked to a higher chance of developing CAD. In this study we aim to test the impact of HbA1c level on perfusion and function metrics derived from myocardial perfusion gated SPECT (MPGS) imaging. Results Two hundred patients were recruited in this study (mean age 58.21 ± 11.53 years; 51% males), of whom 132 patients (66%) were diabetic. Diabetic patients had a higher mean HbA1c of 7.92 ± 1.99 versus 6.05 ± 0.99 in non-diabetics ( p < 0.001). HbA1c% was negatively correlated to LVEF% (r = − 0.262; p < 0.001) and HDL (r = − 0.316; p < 0.001), though, it was positively correlated to ESV (r = 0.221; p = 0.002) and EDV (r = 0.291; p < 0.001). Patients with HbA1c% > 6.5 compared to ≤ 6.5%, had lower LVEF% of 53.17 ± 14.55 vs. 57.8 ± 12.61 ( p = 0.017), lower HDL of 1.046 ± 0.262 vs. 1.196 ± 0.295 ( p < 0.001), more LVEF < 50% (30% vs. 15.6%; p = 0.017), ESV > 44 ml (38.2% vs. 20%; p = 0.005), and WMA (24.5% vs. 12.2%; p = 0.027), hypertension (77.3% vs. 54.4%; p = 0.001) and dyspnea (27.3% vs. 15.6%; p = 0.047), however, with less chest pain (70.9% vs. 83.3%; p = 0.039). Diabetic patients with HbA1c% > 7.5 had lower LVEF% (52.0 ± 14.59 vs. 57.6 ± 11.55; p = 0.018) and HDL (1.005 ± 0.239 vs 1.148 ± 0.273; p < 0.002), more LVEF < 50% (33.3% vs. 14.5%; p = 0.011), ESV > 44 ml (41.3% vs. 20.3%; p = 0.009), WMA (30.2% vs. 11.6%; p = 0.008), and EDV > 100 ml (34.9% vs. 18.8%; p = 0.037). No significant relation was found between HbA1c% and perfusion variables. Conclusions Elevated HbA1c% was associated with multiple abnormal MPGS function parameters including lower LVEF, greater ESV, and more WMA. The same was observed in the diabetic group, together with greater EDV. No significant relation was detected between HbA1c% and perfusion parameters. The effect of impaired glycemic control on cardiac function parameters, even in absence of significant effect on perfusion, could be an alarming sign, while interpreting MPGS studies, both in known diabetic patients and in those with probably insulin resistance but not known to be diabetic. Such findings may be calling for further investigations, to uncover the true mechanisms behind cardiac dysfunction and the possibility of associated microvascular disease.