A practical nomogram incorporating frontal QRS-T angle and aldosterone for early identification of cardiac sarcoidosis

Background Cardiac involvement is a major cause of morbidity and mortality in sarcoidosis, yet its diagnosis remains challenging. Advanced imaging techniques improve detection, but their use should be reserved for patients with suspicion. Therefore, easily applied tests may safely detect subjects needed for further testing. Objectives To investigate whether the frontal QRS-T angle derived from standard electrocardiography, in combination with plasma aldosterone can aid in risk stratification for cardiac involvement. Methods Newly diagnosed, treatment-naïve patients with biopsy-proven sarcoidosis underwent standardized clinical evaluation including anthropometric measurements, 12-lead ECG, and plasma aldosterone measurements. Cardiac involvement was defined according to contemporary consensus criteria incorporating clinical features, imaging, and arrhythmic manifestations. Continuous variables are expressed as median with interquartile ranges. Results Among 359 patients (39% men), 75 (21%) had cardiac involvement. Cardiac involvement was more frequent in men than women (29% vs 15%; p=0.006). Frontal QRS-T angle was higher in cardiac sarcoidosis (CS) vs non-CS (37 [13, 59]° vs 22 [9, 337]°; p<0.001). Plasma aldosterone was also higher in CS (156 [108, 245]pg/ml vs 141 [96, 197]pg/ml; p=0.05). In multivariable analysis, independent predictors were male sex (OR 2.03; p=0.007), aldosterone (OR 1.004; p=0.001), and Frontal QRS-T angle (OR 1.020; p<0.001). The combined model yielded an area under the curve of 0.846, with sensitivity 0.310 and specificity 0.962 (Figure 1) used to construct a nomogram aiming to indicate those subjects with a higher probability of having CS (Figure 2). The graphical structure of the nomogram (points range 0-100) enables clinicians to assign points to each variable (up to 20 points for male sex, up to 85 points for wide frontal QRT-T angle and up to 100 points for high plasma aldosterone levels close to 1,000 pg/ml) and derive a cumulative score corresponding to the predicted probability of cardiac involvement. Conclusions In this cohort of patients with sarcoidosis, cardiac involvement was present in 21% and was more frequent in men. The frontal QRS–T angle and plasma aldosterone levels were significantly higher in patients with cardiac sarcoidosis and, together with male sex, emerged as independent predictors of cardiac involvement. A combined model including these variables showed good discriminatory ability, supporting the use of a nomogram based on simple, routinely available measures to identify patients with a very low likelihood of cardiac involvement and potentially defer further testing.Figure 1Figure 2