Reversible Cardiomyopathy in Polyarteritis Nodosa: A Case Report.

Polyarteritis nodosa (PAN) is a rare vasculitis that affects the medium-sized arteries, often involving numerous organ systems, including the heart. In this report, we present a case of a 26-year-old male with a two-month history of systemic symptoms, abdominal pain, and intrinsic acute kidney injury, who ultimately developed acute hypoxic respiratory failure secondary to acute pulmonary edema. His echocardiogram was notable for biventricular systolic dysfunction with reduced ejection fraction and regional wall motion abnormalities, but no coronary angiogram was pursued. His cardiac magnetic resonance imaging (MRI) study did not demonstrate evidence of myocarditis per Lake Louise criteria. Renal biopsy was consistent with medium-vessel vasculitis, confirming the diagnosis of PAN. He was initiated on immunosuppression with methylprednisolone and cyclophosphamide, and subsequently placed on guideline-directed medical therapy (GDMT) with metoprolol, sacubitril-valsartan, and dapagliflozin. At one-year follow-up, his symptoms had resolved, and his ejection fraction had normalized. Our case uniquely describes a cardiomyopathy phenotype that was likely stress-mediated in the context of active inflammation and was reversible with immunosuppression and GDMT, without the need for revascularization.