Background/Purpose .Heart involvement is common in Systemic Sclerosis (SSc), even if often clinically silent, and represents one of the leading cause of death in these patients.  The aim of our study was to define the role of cardiac troponin T (cTnT) and NT-proBNP to identify a cardiac involvement.

Methods .cTnT and NT-proBNP levels were evaluated in 200 consecutive SSc patients (mean age: 58.7 ± 13.9 years; mean disease duration: 11.1 ± 9.0 years; diffuse disease: 42.0%; anti-Scl70 positivity: 45.5%) from 2008 and 2013.  Data regarding disease subtype and organ involvement were available for the entire cohort and all patients underwent: electrocardiogram (EKG), echocardiography and pulmonary function test (PFTs). All SSc-related deaths were registered during a mean follow-up of 40.8±18.7 months.

Results . cTnT levels were above the normal limit in 79 (39.5%) SSc patients (mean levels in positive patients: 0.06 ± 0.08 ng/ml). NT-proBNP levels were above the cut-off limit of 125 ng/ml, recommended by the manufacturer, in 79 patients (39.5%) and 51 of these patients presented also increased levels of cTnT. The increased cTnT levels were associated with diffuse skin involvement and skeletal myositis (p<0.0001; p=0.006 respectively) and directly correlated with skin score (R=0.27; p<0.0001). Patients with high cTnT levels presented a lower left ventricular ejection fraction (LV-EF) (59.5±9.3%) and higher pulmonary arterial systolic pressure on echocardiography (37.7±16.8 mmHg) compared to patients with normal cTnT values (63.1±4.9%, p=0.04; 28.3±6.8 mmHg, p<0.0001). These patients, furthermore, presented more frequently a right bundle branch block on EKG  with respect to patients without increasing of cTnT (19.7% vs.7.0%; p=0.008). In our cohort 28 patients (14%) presented a LV-EF <55% and the sensitivity of increased cTnT levels (>0.014 ng/ml) in the detection of depressed myocardial contractility was 67.8% and its specificity was 66.8%. It is also noteworthy that its negative predictive value in the assessment of depressed LV-EF was 92%. During the follow-up, 18 SSc-related death occurred; 10 of these were directly related to cardiac involvement (sudden cardiac death or heart failure) and  all occurred in patients with increased cTnT levels. Cumulative survival estimated by Kaplan-Mayer curve was worse in patients with increased baseline levels of cTnT (X²=21.2, p<0.0001). Died patients presented higher levels of cTnT (0.11±0.03 ng/ml) and of NT-proBNP (7193±5691.3 pg/ml) and lower LV-EF (52.5±11.9%) with respect to 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).

Conclusion . The cTnT levels were increased in up to 40% of the SSc patients, revealing that myocardial involvement is more relevant in scleroderma disease than appreciated previously.  cTnT may provide an opportunity to screen non-invasively SSc patients for subclinical heart involvement. The more impaired systolic function and more frequent EKG abnormalities in SSc patients with increased TnT levels, suggest that cTnT may be a novel biomarker of cardiac damage. Our data on survival suggest it as a possible prognostic biomarker of SSc-related death.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/troponin-t-as-a-diagnostic-and-prognostic-biomarker-of-primary-cardiac-involvement-in-systemic-sclerosis/