Background Heart involvement is common in Systemic Sclerosis (SSc), even if often clinically silent, and represent one of the leading cause of death in these patients.
Objectives The aim of our study was to define the role of cardiac troponin T (cTnT) and NT-proBNP to identify cardiac involvement in SSc.
Methods From 2008 to 2013 high sensitivity cTnT and NT-proBNP were measured in 200 consecutive SSc patients and in 30 sex and aged matched healthy controls. Data regarding disease subtype and organ involvement were available for the entire cohort. All SSc-related deaths were registered.
Results cTnT levels and NT-proBNP values were higher in scleroderma patients (cTnT: 0.03±0.006 ng/ml and NT-proBNP: 898.8±3063.8 pg/ml) than in healthy controls (cTnT: 0.006±0.0004 ng/ml and NT-proBNP: 90.6±70.9 pg/ml, p<0.00001 for both comparisons). cTnT levels were upper the normal limit in 79 SSc patients (39.5%), 54 of whom (68.4%) complained cardiac symptoms, while 25 (31.6%) were asymptomatic. NT-proBNP levels were above the cut-off limit of 125 ng/ml, recommended by the manufacturer, in 79 patients (39.5%) and 51 presented also increased levels of cTnT. The levels of NT-proBNP directly correlate with the cTnT levels (R=0.4; p<0.0001) and were higher in patients with increase of cTnT (2154.1±4691.8 pg/ml) compared to patients without cTnT increase (115.5±145.4 pg/ml; p<0.0001).During the follow-up, 18 SSc-related death occurred; 10 of these were directly related to cardiac involvement (sudden cardiac death or heart failure, related and unrelated to pulmonary arterial hypertension) and all occurred in patients with increased cTnT levels and NT-proBNP>125 pg/ml. Cumulative survival estimated by Kaplan-Mayer curve was worse in patients with increased baseline levels of cTnT and NT-proBNP. Died patients presented higher levels of cTnT (0.11±0.03 ng/ml) and of NT-proBNP (7193.1±5691.6 pg/ml) and lower left ventricular-ejection fraction (LV-EF) (52.5±11.9%) than survivors (cTnT: 0.02±0.05 ng/ml; NT-proBNP: 585.8±2517.3 pg/ml; LV-EF: 61.9±6.6%; p<0.001 for all comparisons). At ROC curve, cTnT>0.019 ng/ml showed the best specificity (75%) with a sensitivity of 100% to identify patients with poor outcome (AUROC=0.90, p<0.0001), while the best threshold for NT-proBNP to identify patients at risk of cardiac death was 618 pg/ml, with a specificity of 90% and a sensitivity of 100% (AUROC=0.97, p<0.0001). Considering all SSc cohort, 25 patients (34.2%) presented NT-proBNP>618 mg/dl and an increase of cTnT with respect to only 2 patients (1.7%) with increased of NT-proBNP but without cTnT elevation (p<0.0001).
Conclusions cTnT and NT-proBNP should be routinely evaluated in all SSc patients, even if asymptomatic, in order to identify at early stages those with a subclinical heart disease and a bad cardiac outcome. Patients with cTnT>0.019 ng/ml and NT-proBNP >618 pg/ml have an high risk of cardiac death and need to be strictly monitored.
Disclosure of Interest None declared