The purpose of this study was to evaluate the prognostic value of HRV in elderly patients with multivessel coronary artery disease (MVCAD) on the background of invasive and non-invasive treatment. Methods and Results: This study included 254 patients over age 65 with lesions of the left trunk of the left coronary artery in combination with lesions of 2 or more coronary arteries. To assess HRV, all patients underwent 24-hour Holter ECG monitoring at baseline and one year later. Depending on the treatment strategy, patients were divided into 3 groups. Group 1 consisted of 99 patients who, in addition to the standard treatment, underwent PSI (from 1 to 4 stents); Group 2 included 86 patients who, in addition to the standard treatment, underwent CABG (from 2 to 4 shunts); Group 3 included 69 patients who received only optimal drug therapy (ODT). The results have shown that a decrease in HRV is an independent predictor of complications associated with an increase in coronary insufficiency in CAD patients. Such indicators of HRV as SDNN, SDNNi, TP, VLF, and LF have a significant positive predictive value in patients undergoing ODF and/or undergoing PCI. For patients undergoing CABG, at least in the first year after surgery, HRV cannot be considered as an independent prognostic marker. For elderly patients with MVCAD, 24-hour Holter ECG monitoring with subsequent analysis of HRV is recommended to assess the recovery process and pharmacotherapy.