pressure in my chest; 10 clots and a saddle clot that was blocking 60% of the right pulmonary artery and 40% of the left. He was believed to have "thrown a clot."; like an asthma attack/ 2-3 months later and all of a sudden, his attacks got really bad; Atrial fribrillation; This spontaneous case was reported by a patient and describes the occurrence of PULMONARY ARTERY THROMBOSIS (10 clots and a saddle clot that was blocking 60% of the right pulmonary artery and 40% of the left. He was believed to have "thrown a clot."), ATRIAL FIBRILLATION (Atrial fribrillation) and CHEST DISCOMFORT (pressure in my chest) in a 74-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 004C21A, 001A21A and 031120A) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.     No Medical History information was reported.   On 30-Jan-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 27-Feb-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On 15-Nov-2021, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On 17-Mar-2022, the patient experienced PULMONARY ARTERY THROMBOSIS (10 clots and a saddle clot that was blocking 60% of the right pulmonary artery and 40% of the left. He was believed to have "thrown a clot.") (seriousness criteria hospitalization and medically significant) and ATRIAL FIBRILLATION (Atrial fribrillation) (seriousness criterion medically significant). In April 2022, the patient experienced CHEST DISCOMFORT (pressure in my chest) (seriousness criterion hospitalization). On an unknown date, the patient experienced ASTHMA (like an asthma attack/ 2-3 months later and all of a sudden, his attacks got really bad). The patient was treated with WARFARIN SODIUM (COUMADIN) at an unspecified dose and frequency. At the time of the report, PULMONARY ARTERY THROMBOSIS (10 clots and a saddle clot that was blocking 60% of the right pulmonary artery and 40% of the left. He was believed to have "thrown a clot."), ATRIAL FIBRILLATION (Atrial fribrillation) and CHEST DISCOMFORT (pressure in my chest) had resolved and ASTHMA (like an asthma attack/ 2-3 months later and all of a sudden, his attacks got really bad) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In April 2022, Cardiac stress test: Blood was not perfusing his heart properly. In April 2022, Computerised tomogram thorax: blood clots in lungs had dissolved and pulmonary artery was dilated.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter did not provide any causality assessments.   No concomitant medications were reported. Asthma includes shortness of breath,unable to breathe properly and Extreme trouble breathing.  He experienced shortness of breath, tightness in his chest, and inability to breathe properly. This was described similar to an asthma attack like when you would need an inhaler. He spoke with his primary care doctor who put him on a 9 day course of steroids. He repeated the steroids for 3 courses and had been used a nebulizer inhaler. 2-3 months later, and all of a sudden, his attacks got really bad. He had a primary care doctor's appointment on 17-Mar-2022 where he had extreme trouble breathing while getting out of the car and going into the office. He was placed on a heart monitor while there and was in atrial fibrillation. Emergency services were called, and he took to the emergency room. He was noticed to have 10 clots and a saddle clot that was blocking 60 percent of the right pulmonary artery and 40 percent of the left. He was believed to had thrown a clot. He was hospitalized in intensive care for 7-8 days where they evaluated for potential intervention. He became stable while there and was placed on Coumadin prior to discharge.  At the end of April, he returned to the emergency room for pressure in his chest. His right pulmonary artery was dilated, and he received a stress test which he failed. Blood was not perfusing his heart properly and he received a heart catheterization. This catheterization was successful.  He had no previous heart issues prior to these events and had never experienced anything like  Company comment:This spontaneous case concerns a 74-year-old male patient with no medical history reported, who experienced the unexpected serious (hospitalization and medically significant) AESI of Pulmonary artery thrombosis, unexpected serious (medically significant) AESI of Atrial fibrillation, unexpected serious (hospitalization) event of Chest discomfort and non-serious event of Asthma that occurred in the context of third dose of mRNA-1273 vaccine. Patient experienced shortness of breath, tightness in his chest, and inability to breathe properly. This was described like an asthma attack like when you would need an inhaler. Upon contacting doctor, he started a 9-day course of steroids. He repeated the steroids for 3 courses and is using a nebulizer. Approximately 2-3 months later, suddenly his attacks got bad where he had extreme trouble breathing while getting out of the car and going into the office. He was placed on a heart monitor while there and was found to be in atrial fibrillation. Emergency services were called, after examination, he was noticed to have 10 clots and a saddle clot that was blocking 60 percent of the right pulmonary artery and 40 percent of the left. He was believed to had thrown a clot. He was hospitalized in intensive care for 7-8 days where they evaluated for potential intervention. He was stabilized and was placed on Coumadin prior to discharge. At the end of April, patient revisited emergency for pressure in his chest. On examination his right pulmonary artery was dilated, and failed stress test. Blood was not perfusing to his heart properly hence received a successful heart catheterization. The outcome of the event's Pulmonary artery thrombosis, Atrial fibrillation and Chest discomfort was reported as resolved and event Asthma reported as unknown. Patients elderly age could be a risk factor for the event's Pulmonary artery thrombosis and Atrial fibrillation. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.; Sender's Comments: This spontaneous case concerns a 74-year-old male patient with no medical history reported, who experienced the unexpected serious (hospitalization and medically significant) AESI of Pulmonary artery thrombosis, unexpected serious (medically significant) AESI of Atrial fibrillation, unexpected serious (hospitalization) event of Chest discomfort and non-serious event of Asthma that occurred in the context of third dose of mRNA-1273 vaccine. Patient experienced shortness of breath, tightness in his chest, and inability to breathe properly. This was described like an asthma attack like when you would need an inhaler. Upon contacting doctor, he started a 9-day course of steroids. He repeated the steroids for 3 courses and is using a nebulizer. Approximately 2-3 months later, suddenly his attacks got bad where he had extreme trouble breathing while getting out of the car and going into the office. He was placed on a heart monitor while there and was found to be in atrial fibrillation. Emergency services were called, after examination, he was noticed to have 10 clots and a saddle clot that was blocking 60 percent of the right pulmonary artery and 40 percent of the left. He was believed to had thrown a clot. He was hospitalized in intensive care for 7-8 days where they evaluated for potential intervention. He was stabilized and was placed on Coumadin prior to discharge. At the end of April, patient revisited emergency for pressure in his chest. On examination his right pulmonary artery was dilated, and failed stress test. Blood was not perfusing to his heart properly hence received a successful heart catheterization. The outcome of the event's Pulmonary artery thrombosis, Atrial fibrillation and Chest discomfort was reported as resolved and event Asthma reported as unknown. Patients elderly age could be a risk factor for the event's Pulmonary artery thrombosis and Atrial fibrillation. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.