Nociceptive disorders in patients with microvascular angina pectoris and patients with silent myocardial ischemia

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): North-western State Medical University named after I.I.Mechnikov The purpose of this study was to study the diagnostic value of the nociceptive flexor reflex (NFR) method in patients with MVA and patients with silent myocardial ischemia. Materials and methods. A total of 158 people were examined, including 131 patients with ischemic heart disease and 31 healthy volunteers (control group). Patients with coronary artery disease were represented by three groups: patients with MVA - 49 people (main group), patients with angina pectoris due to atherosclerotic lesions of the coronary arteries - 40 people (comparison group 1), patients with a diagnosis of painless myocardial ischemia (SMI) - 42 people (comparison group 2). To determine pain indicators, the method of nociceptive flexor reflex (NFR) was used during electrical stimulation of the sural nerve (Nicolet Viking (USA)). Results. The coefficient (k) of pain threshold / reflex threshold (Pb / Pr) in the control group of healthy volunteers was 0.94 ± 0.01, which corresponds to the accepted norms (1-0.9) according to literature data. In the study of NFR in patients with MVA, a decrease in the pain threshold, reflex threshold and ratio (Pb / Pr) was revealed. In the MVS group, PB= 9.5 ± 0.58 mA; Pr = 12.1 ± 0.58 mA; Pb / Pr = 0.78 ± 0.02. The pain threshold in patients with MBS turned out to be statistically significantly lower in comparison with comparison group 1 and comparison group 2 and control group (p <0.01; p <0.001; p <0.001, respectively). The reflex threshold in patients with MVA is statistically significantly lower than in comparison group 1, comparison group 2 (SIM) and control group (p <0.02; p <0.001; p <0.01, respectively). In patients with angina pectoris, PB = 13.8 ± 0.31 mA; Pr = 14.8 ± 0.33 mA; Pb / Pr = 0.94 ± 0.01. In patients with SIM, PB = 24.9 ± 0.99 mA; Pr = 22.9 ± 0.79 mA; Pb / Pr = 1.2 ± 0.02. There was a significant increase in the pain threshold, reflex threshold and the pain threshold / reflex threshold ratio in the group of patients with silent myocardial ischemia compared with similar indicators in the control group, the main group and comparison group 1 (p <0.001; p <0.001; p <0.001 respectively). Conclusions. In patients with MVA compared with healthy individuals in the control group and comparison groups, there is a decrease in NFR indices, which indicates the presence of nociceptive disorders. In patients with SIM, the reflex threshold values are lower in value than the pain threshold. Thus, in patients with SIM the muscle response occurs before the onset of the subjective sensation of pain.