Clinical significance of geriatric nutritional risk index in risk stratification of acute myocarditis

The clinical course of acute myocarditis varies widely, making accurate prognostication difficult. Nutritional assessment aids risk stratification in various cardiovascular diseases; however, its role in myocarditis remains unclear. This study examined the association between Geriatric Nutritional Risk Index (GNRI)-defined nutritional risk, and prognosis in acute myocarditis. We analyzed admission data on patients with acute myocarditis hospitalized via emergency medical services from the multicenter Tokyo CCU Network Database between January 2017 and December 2022. Nutritional risk was assessed using the GNRI (≥ 98 normal nutrition; 92 to < 98 low; 82 to < 92 moderate; ≤82 severe). The primary outcome was in-hospital death, and secondary outcomes included hospital length of stay (LOS) and cardiovascular care unit LOS. Multivariable Cox regression assessed the association between GNRI-defined nutritional risk and outcomes, adjusting for patient characteristics. Among 402 patients, the median age was 43 years [27–66], and 24.9% presented with shock. GNRI categories were as follows: normal nutrition 41.5%, low 20.6%, moderate 22.9%, and severe 14.9%. Compared with the normal-nutrition group, the severe-risk group had a higher hazard of in-hospital death (adjusted hazard ratio (aHR) = 12.2; 95% CI 2.64–56; P = 0.0025). Each one-point decrease in GNRI was associated with higher in-hospital mortality after multivariable adjustment (aHR = 1.06; 95% CI 1.03–1.09; P < 0.001). The trend remained similar in models adjusted for inflammation. GNRI-defined nutritional risk was associated with poorer prognosis, and may provide additional prognostic information in patients with acute myocarditis.