The article provides a detailed description of a clinical case report of acute massive pulmonary artery thromboembolism (PATE) in an elderly female patient. She was diagnosed with a carrier state of polymorphism of genes associated with impairment in the folate cycle MTHFR:677 - TT, MTRR:66 - AG and polymorphisms associated with disordered blood coagulation system F13 - GT; ITGB3:1565 - TC; SERPINE1 (PAI-1):675 - 4G4G. She was also found to have hyperhomocysteinemia - 67.1 μmol/l and hyperaggregation syndrome. Timely prescribed antithrombotic therapy and an agent containing in its base folic acid, vitamins B6 and B12 after surgical intervention in the scope of endovascular recanalization of pulmonary arteries and additional thromboembolic therapy resulted in a favourable outcome.