cardiomegaly; Left Atrial enlargement; dizzy lightheaded, like she was going to faint; ransient viral illness, some arthralgia and myalgia; ransient viral illness, some arthralgia and myalgia; ransient viral illness, some arthralgia and myalgia; This spontaneous report was received from a physician and refers to a 68-year-old female patient. The patient's medical history included splenectomy performed 30 years ago and a pacemaker insertion. The patient's concurrent conditions included heart rhythm problem with pacemaker in place, high blood pressure, reflux, asthma and allergy to acetaminophen (+) hydrocodone bitartrate (NORCO) and peanuts. The patient's concomitant medications included procaterol hydrochloride (PROAIR), coenzyme q, fluticasone propionate (FLONASE), loratadine (CLARITIN), omega-3 fish oil, pravastatin sodium (PRAVACHOL), rivaroxaban (XARELTO), sacubitril (+) valsartan(ENTRESTO) and cimetidine (TAGAMET).  On 25-JUL-2019, the patient was vaccinated with the first dose of measles, mumps, and rubella (wistar ra 27-3) virus vaccine, live (M-M-R II) injection (dose, route of administration, lot# and expiration date were not reported) for prophylaxis as she was working in health care facility.  On an unknown date in 2019, the patient started to experience transient viral illness, arthralgia and myalgia. Due to aforementioned events, she missed some time from work. On 27-AUG-2019, the patient received the second dose of measles, mumps, and rubella (wistar ra 27-3) virus vaccine, live (M-M-R II) injection (dose, route of administration, lot# and expiration date were not reported). On an unknown date in 2019, after the second dose of the vaccine, the patient experienced arthralgia, myalgia and dyspnea. She again missed some time from work due to these symptoms. Computed tomography (CT) completed on 29-AUG-2019, showed cardiomegaly and left atrial enlargement. The physician reported that the patient was given sacubitril (+) valsartan (ENTRESTO) as treatment for cardiomegaly and left atrial enlargement. On 04-SEP-2019, the patient went to an emergency room (ER) due to a two-week history of chest pain which worsened with deep breathing and exertion. She also complained of feeling dizzy, lightheaded, like she was going to faint. On the same day, the patient was admitted to a hospital. The reporter stated that the patient was discharged within 48 hours. An echocardiography (ECHO) performed on 17-OCT-2019, showed that the patient had an ejection fraction (EF) of 20 percent. The physician highlighted that an ECHO performed on 17-JUN-2019 showed 60 percent EF. On 30-OCT-2019, the patient was admitted to the same hospital due to shortness of breath. The physician stated that the patient received an unspecified treatment during her stays in the hospital. At the reporting time, the patient had not recovered from the events and it was unknown if she had been discharged from the hospital.   The causality assessment was not provided. The physician stated that the events caused significant disability or incapacity, and he considered the events of cardiomegaly and left atrial enlargement as life-threatening.  Upon internal review, the events of cardiomegaly and left atrial enlargement were determined to be medically significant.