arrhythmia that was worse during the episode; Her heart was skipping beats; Swelling in her legs from her knees to her toes; slight enlargement of the heart; headache on the left side of her head; Rash; Fever blisters; bumps on her body; Joint pain; This spontaneous case was reported by a consumer and describes the occurrence of ARRHYTHMIA (arrhythmia that was worse during the episode) in a 77-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 037B21A and 030A21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Concurrent medical conditions included Arrhythmia. Concomitant products included ATENOLOL for Arrhythmia.   On 10-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 07-Apr-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. In May 2021, the patient experienced ARRHYTHMIA (arrhythmia that was worse during the episode) (seriousness criterion medically significant), EXTRASYSTOLES (Her heart was skipping beats), PERIPHERAL SWELLING (Swelling in her legs from her knees to her toes), CARDIOMEGALY (slight enlargement of the heart) and HEADACHE (headache on the left side of her head). In 2021, the patient experienced ORAL HERPES (Fever blisters), SWELLING (bumps on her body), ARTHRALGIA (Joint pain) and RASH (Rash). In May 2021, ARRHYTHMIA (arrhythmia that was worse during the episode), EXTRASYSTOLES (Her heart was skipping beats), PERIPHERAL SWELLING (Swelling in her legs from her knees to her toes), CARDIOMEGALY (slight enlargement of the heart) and HEADACHE (headache on the left side of her head) had resolved. At the time of the report, ORAL HERPES (Fever blisters), SWELLING (bumps on her body), ARTHRALGIA (Joint pain) and RASH (Rash) had not resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Blood pressure measurement: high (High) Her blood pressure shot up.. On an unknown date, Chest X-ray: slight enlargement of the heart (abnormal) slight enlargement of the heart. On an unknown date, Laboratory test: slight enlargement of the heart (abnormal) slight enlargement of the heart. On an unknown date, Scan brain: slight enlargement of the heart (abnormal) slight enlargement of the heart.         No treatment medication was reported by patient. Patient reported that about a month & a half after the 2nd dose she had swelling in her legs from her knees to her toes, her blood pressure shot up, she had a headache on the left side of her head, and her heart was skipping beats. She went to the ER with these symptoms & they found slight enlargement of the heart and symptoms got resolved after 2 days without treatment. Patient reported that she had been following up with PCP & cardiologist for clinical outcome. Company comment:This is a Spontaneous case concerns of female patient of 77 years with medical history of Arrthymia, who experienced the unexpected serious event Arrythmia (Medically significant) and unexpected AESI event Extrasystoles and unexpected non serious events of Peripheral swelling, Cardiomegaly, Oral herpes, swelling and Arthralgia. The event Arrythmia, Peripheral swelling, Extrasystoles, and Headache occurred approximately I month after the second dose of mRNA1273 vaccine which resolved in the same month. Reportedly, Patient had oral Herpes, Swelling, Arthralgia and Rash in the same year of which dates are unknown and not resolved. On an unknown date, Blood pressure measurement was high, and slight enlargement of the heart (abnormal) was reported with Chest X-ray and Laboratory test. No additional information is available at the time of this report. The benefit-risk relationship of mRNA-1273 in not affected by this report.; Sender's Comments: This is a Spontaneous case concerns of female patient of 77 years with medical history of Arrthymia  who experienced the unexpected serious event Arrythmia (Medically significant) and unexpected AESI event Extrasystoles and unexpected non serious events of Peripheral swelling, Cardiomegaly, Oral herpes, swelling and Arthralgia. The event Arrythmia, Peripheral swelling, Extrasystoles, and Headache occurred approximately I month after the second dose of mRNA1273 vaccine which resolved in the same month. Reportedly, Patient had oral Herpes, Swelling, Arthralgia and Rash in the same year of which dates are unknown and not resolved. On an unknown date, Blood pressure measurement was high, and slight enlargement of the heart (abnormal) was reported with Chest X-ray and Laboratory test. No additional information is available at the time of this report. The benefit-risk relationship of mRNA-1273 in not affected by this report.