Case Presentation: A previously healthy 39-year-old female presented with symptoms of nausea, vomiting, generalized fatigue, and lightheadedness for a couple of days. The physical examination was unremarkable. Labs showed an elevated N-terminal pro-BNP, troponin T, and C-reactive protein. A urine drug screen was positive for amphetamines. ECG initially showed mild sinus tachycardia and right bundle-branch block, but the patient later developed a high-degree AV block necessitating emergent transvenous pacing. A transthoracic echocardiogram (TTE) revealed a left ventricular ejection fraction of 50-55% with increased left ventricular wall thickness without any regional wall motion abnormalities. A small pericardial effusion was seen that was without tamponade physiology. The patient underwent left heart catheterization, which revealed angiographically normal coronary arteries with basal inferior wall hypokinesis. Cardiac MRI indicated mild subepicardial delayed enhancement in the lateral wall, suggestive of myocarditis. A cardiac biopsy confirmed myocarditis but no viral cytopathic effect was noted. During the hospital stay, the patient’s condition deteriorated requiring an intra-aortic balloon pump (IABP) and milrinone support. A provisional diagnosis of fulminant myocarditis with potential etiologies including viral myocarditis or toxic myocarditis secondary to amphetamine use was made. However, extensive infectious workup including Karius testing was done, which was unremarkable. She was started on intravenous steroids. Gradually, the patient’s condition improved. She successfully came off milrinone; the IABP was removed, and her ejection fraction improved to 60-65%. The patient was eventually discharged on a tapering dose of prednisone after substance abuse counseling.
Discussion: Myocarditis is a significant cause of sudden cardiac death in young individuals, with autopsy findings attributing it to 2% to 42% of cases. Although the most common cause of myocarditis is viruses, a detailed drug intake history should be taken, as cocaine, amphetamines, and ethanol have been implicated in drug-induced myocarditis. The most common symptoms of myocarditis include chest pain, fever, and dyspnea, although the presentation can vary widely. Although an electrocardiogram, elevated CRP, troponins, TTE, and cardiac MRI may suggest the presence of myocarditis, a definitive diagnosis of myocarditis can only be made through endomyocardial biopsy using Dallas criteria. Acute myocarditis is frequently reversible, but cases with refractory heart failure or cardiogenic shock may necessitate temporary mechanical circulatory support such as intra-aortic balloon pumps and ionotropic support. In fulminant cases, immunosuppression with corticosteroids can be considered, though evidence supporting this approach is limited. Patients diagnosed with myocarditis face a 10-year all-cause mortality rate of approximately 25.5%, with younger patients experiencing higher mortality. To mitigate risks such as cardiac remodeling and sudden cardiac death, patients should abstain from sports and vigorous exercise for 3–6 months.
Conclusions: Myocarditis remains a serious disease with a high mortality rate, necessitating ongoing follow-up to detect complications early. While viral myocarditis is the most common form, toxic myocarditis is rare and often underdiagnosed. Particular vigilance is needed in young patients, where illicit drug use should be ruled out.