Predictors of left ventricular dysfunction in young patients with acute myocarditis

Background

Acute myocarditis (AM) is a frequent cause of Cardiology admissions in young adults. It represents a heterogeneous clinical entity, ranging from mild, self-limited disease to severe myocardial dysfunction. Identifying predictors of left ventricular (LV) systolic dysfunction remains clinically relevant for risk stratification, particularly in the acute phase of the disease.

Purpose

To identify clinical, inflammatory, and imaging predictors of LV dysfunction in patients hospitalized with AM.

Method

We include all patients admitted with AM who underwent cardiac magnetic resonance (CMR) imaging during index hospitalization between 2015 and 2024. LV systolic dysfunction was defined as a left ventricular ejection fraction (LVEF) <52% in men and <54% in women. Clinical characteristics, laboratory parameters, and CMR findings were collected. Univariable logistic regression was performed to identify factors associated with reduced LVEF. Based on univariate significance (p<0,05) and other clinically relevant variables a multivariable logistic regression model was built.

Results

A total of 157 patients were included; 81.5% were male, with a median age of 35 years (IQR 24–49). The prevalence of hypertension was 10.2%, dyslipidaemia 15.9%, diabetes mellitus 3.2%, and active smoking 36.3%. Prior ischemic heart disease was present in 2.5% and atrial fibrillation in 0.6%.

On CMR, mean LV end-diastolic volume was 88 ±19mL, mean LVEF 56 ±7.8%, and right ventricular EF 55 ±6.5%. Myocardial oedema involved ≤2 segments in 15.4% of patients and >2 segments in 84.6%, with a median of 6 (IQR 3–8) segments involved. 29 patients (18.5%) developed LV dysfunction, with a median LVEF of 48% (IQR 43–50). Compared with patients with preserved systolic function, those with reduced LVEF had lower lymphocyte counts (30.6 ±11.6% vs 36.7 ±11.9%; p=0.017), higher neutrophil-to-lymphocyte ratio (NLR) (2.6 [2.1–3.1] vs 2.0 [1.6–2.5]; p=0.001), higher C-reactive protein (CRP) levels (8.7 [5.0–14.6] vs 5.9 [2.2–9.4]; p=0.020), and higher NT-proBNP levels (1460 [347–6207] vs 494 [236–1001] pg/mL; p=0.033). Troponin levels and myocardial oedema were higher in patients with reduced LVEF but this difference did not reach statistical significance. In univariable logistic regression, lymphocyte count (OR 0.96, 95% CI 0.93–0.99), NLR (OR 2.72, 95% CI 1.20–6.16), CRP (OR 1.49, 95% CI 1.02–2.18), and NT-proBNP (OR 1.43, 95% CI 1.04–1.97) were associated with LV systolic dysfunction. In the multivariable model, only CRP remained independently associated with reduced LVEF (OR 1.68, 95% CI 1.04–2.70) (Figure 1).

Conclusions

In patients with AM, inflammatory markers including lymphopenia, elevated NLR, and increased CRP levels were associated with LV systolic dysfunction. Among these, only CRP remained an independent predictor, highlighting the central role of systemic inflammation in myocardial dysfunction during the acute phase of myocarditis.Predictors of LV dysfuncionFor image description, please refer to the figure legend and surrounding text.