trembling and shakiness in my arms & legs; existing tinnitus got worse with the ringing in my ears extremely severe.; severe heat exhaustion; I felt nauseous; felt like maybe I was having a heart attack; I broke out in a massive sweat with big beads of sweat; I could not get comfortable; sensation of getting hot; a very weird feeling / I just did not feel right the entire summer / I feel like my brain is not functioning; very dizzy; anxious / felt massive waves of anxiety; My entire body felt sick; my stomach felt sick; This spontaneous case was reported by a patient and describes the occurrence of MYOCARDIAL INFARCTION (felt like maybe I was having a heart attack) in a 47-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Concurrent medical conditions included Tinnitus.   In April 2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 14-May-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On 18-May-2021, the patient experienced FEELING HOT (sensation of getting hot), FEELING ABNORMAL (a very weird feeling / I just did not feel right the entire summer / I feel like my brain is not functioning), DIZZINESS (very dizzy), ANXIETY (anxious / felt massive waves of anxiety), ILLNESS (My entire body felt sick) and ABDOMINAL DISCOMFORT (my stomach felt sick). On 22-Jul-2021, the patient experienced MYOCARDIAL INFARCTION (felt like maybe I was having a heart attack) (seriousness criterion medically significant), HYPERHIDROSIS (I broke out in a massive sweat with big beads of sweat), DISCOMFORT (I could not get comfortable) and NAUSEA (I felt nauseous). On an unknown date, the patient experienced TREMOR (trembling and shakiness in my arms & legs), TINNITUS (existing tinnitus got worse with the ringing in my ears extremely severe.) and HEAT EXHAUSTION (severe heat exhaustion). At the time of the report, MYOCARDIAL INFARCTION (felt like maybe I was having a heart attack) had resolved and FEELING HOT (sensation of getting hot), FEELING ABNORMAL (a very weird feeling / I just did not feel right the entire summer / I feel like my brain is not functioning), DIZZINESS (very dizzy), ANXIETY (anxious / felt massive waves of anxiety), ILLNESS (My entire body felt sick), ABDOMINAL DISCOMFORT (my stomach felt sick), HYPERHIDROSIS (I broke out in a massive sweat with big beads of sweat), DISCOMFORT (I could not get comfortable), TREMOR (trembling and shakiness in my arms & legs), TINNITUS (existing tinnitus got worse with the ringing in my ears extremely severe.), HEAT EXHAUSTION (severe heat exhaustion) and NAUSEA (I felt nauseous) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Electrocardiogram: heart sounded fine (normal) heart sounded fine.         On 18May2021, the patient experienced a sensation of getting hot and a very weird feeling. This was after playing in the yard for 40 minutes. The patient got very dizzy and anxious. This lasted for 8 to 10 minutes. The patient's entire body and stomach felt sick. The patient did not feel right the entire summer. On 22-JUL-2021, the patient started to get the same feeling that he had on 18-May-2021. The patient felt like was having a heart attack. The patient felt massive waves of anxiety. He could not get comfortable. This lasted for 15 to 20 minutes. The patient started coming down from the anxiety. After 22-Jul-2021, the patient felt small mini attacks of waves of anxiety with trembling and shakiness in his arms and legs. The patient felt like his brain was not functioning. Something feels amiss.  The patient did notice that if he ate something it would make mini attacks go away. The patient went to go see Physician in late July 2021. The Physician thought that the patient had severe heat exhaustion and had him drink a lot of fluids and electrolytes. The doctor had him wear a heart monitor. The cardiologist read the results of heart monitor. The cardiologist also ordered an electrocardiogram (EKG) and a chest x-ray and observed the patient's heart and its normal. The patient had 4 physician visits.  Company Comment: Based on temporal association between the use of the product and the start date of the reported events and the absence of any other etiology factors, a causal association cannot be excluded. Nausea is consistent with the known safety profile of the vaccine.; Sender's Comments: Based on temporal association between the use of the product and the start date of the reported events and the absence of any other etiology factors, a causal association cannot be excluded. Nausea is consistent with the known safety profile of the vaccine.