MYOCARDIAL PERFUSION AND CARDIOVASCULAR RISK IN PATIENTS WITH LONG-TERM VENTRICULAR PACING IN THE LONG PERIOD
Authors:   Republican Scientific and Practical Center of Pediatric Surgery, Minsk, Republic of Belarus, A. Harypau , I. Patsiayuk ,   Belarusian State Medical University, V. Terehov ,   5th City Clinical Hospital, Minsk, Republic of Belarus
Published: September 2024

Aim. To study myocardial perfusion and assess cardiovascular risk in patients with long-term ventricular pacing in the long period. Materials and methods. The study included 40 young patients (23 men and 17 women) with atrioventricular (AV) blocks and implanted pacemakers (pacers). Group 1 consisted of 20 patients with postoperative AV block after surgical correction of congenital heart disease; group 2 – 20 patients with non-surgical AV block. Age at the time of the study was 22.8 (19.8; 24.0) years in group 1 and 22.5 (20.4; 24.8) years in group 2 (U=181.0, p=0.620). The duration of pacing in the groups was 15.5 (12.8; 18.9) years and 15.7 (14.1; 18.2) years, respectively (U=193.0, p=0.862). At the time of examination, all patients had a dual-chamber pacemaker implanted with 100% ventricular pacing. All patients underwent a general clinical examination and single-photon emission computed tomography of the myocardium. Results. Perfusion disorders were detected in 52.5% of young patients with prolonged ventricular stimulation, regardless of the cause of AV block; in 25% of the subjects they were pronounced. Transient LV myocardial ischemia was detected in 42.5% of individuals included in the study. Significant myocardial ischemia (with an SDS value of >4 points) in patients with prolonged ventricular stimulation, regardless of the cause of AV block, was accompanied by changes in volumetric parameters and impaired LV systolic function during exercise (Stress LV EDVI, Stress LV ESVI, Stress LV EF, ΔEF LV), myocardial systolic thickening (WT-SSS). Transient dilatation (especially in combination with myocardial ischemia) is an unfavorable risk factor for the development of cardiovascular events. A combination of stress-induced ischemia and the “stunning” phenomenon (with a decrease in LVEF by 5% or more) was identified in 15% of patients with prolonged ventricular stimulation, regardless of the cause of AV block, which is an independent predictor of the development of adverse cardiovascular events. A statistically significant relationship was established between the development of myocardial ischemia and the indicators of the difference (delta) in LV wall thickening (ΔWT-SDS) and the difference (delta) in LVEF (ΔLVEF) during the study at rest and during the stress test. A mathematical model has been proposed for calculating the probability of developing transient myocardial ischemia according to SPECT data with the inclusion of these indicators, the area of the ROC curve was AUC=0.854 ((95% CI 0.707 – 0.946), p <0.001, sensitivity 81.8%, specificity 72.4%). Conclusion. In young patients with prolonged ventricular stimulation, regardless of the cause of AV block, significant perfusion disturbances, stress-induced transient ischemia in combination with the phenomenon of “stunning” (decrease in LVEF≥5%), which were accompanied by remodeling and impairment of LV systolic function during load. The identified perfusion disorders may be significant predictors of adverse cardiovascular events in this population.