Cardiomyopathy
Significance and Determinants of Cardiac Troponin I in Patients With Obstructive Hypertrophic Cardiomyopathy

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Serum cardiac troponins have been demonstrated to have important clinical implications in patients with hypertrophic cardiomyopathy (HC). However, little is known about their roles in patients with obstructive HC. The aim of this study was to explore the clinical significance and determinants of serum cardiac troponin I (cTnI) in patients with obstructive HC using cardiovascular magnetic resonance imaging. We investigated the relations between serum cTnI levels and clinical, echocardiographic, and cardiovascular magnetic resonance parameters and assessed the determinants of serum cTnI in 149 consecutive patients with obstructive HC. The median level of serum cTnI was 0.019 ng/ml (interquartile range 0.009 to 0.044). CTnI was elevated (≥0.04 ng/ml) in 42 (28%) of the overall cohort. Patients with elevated cTnI had greater maximum wall thickness (p <0.001), larger left ventricular mass index (LVMI, p <0.001), more frequency of left atrium diameter ≥50 mm (p = 0.020), higher plasma values of N-terminal pro-B-type natriuretic peptide (p <0.001), and less hypertension (p = 0.014). Serum cTnI levels were positively correlated with maximum wall thickness (r = 0.444, p <0.001), LVMI (r = 0.556, p <0.001), N-terminal pro-B–type natriuretic peptide (r = 0.305, p <0.001), left ventricular end-diastolic volume index (r = 0.246, p = 0.002), and left ventricular end-systolic volume index (r = 0.272, p = 0.001) but negatively with left ventricular ejection fraction (r = −0.180, p = 0.028). On multivariate analysis, LVMI was independently associated with both elevated cTnI (odds ratio 1.032, p = 0.001) and increasing serum cTnI levels (β = 0.556, p <0.001). In addition, the presence of hypertension was independently related to less likely elevated cTnI (odds ratio 0.307, p = 0.029) and decreasing levels of serum cTnI (β = −0.165, p = 0.015). In conclusion, levels of serum cTnI are elevated in a significant proportion of our patients. Serum cTnI is associated with multiple parameters of disease severity, suggesting its great significance in assessing cardiac remodeling in patients with obstructive HC. Left ventricular hypertrophy, as indicated by LVMI, is the major determinant of serum cTnI levels.

Section snippets

Methods

We recruited consecutive patients with obstructive HC who were evaluated in Fuwai Hospital (Beijing, China) from November 2008 to June 2013. All subjects underwent a comprehensive cardiac evaluation, including complete medical history, physical examination, 12-lead electrocardiography, 24-hour ambulatory electrocardiographic monitoring, TTE, blood examination, CMR, and coronary angiography. The diagnosis of HC was based on a maximum LV wall thickness ≥15 mm (or ≥13 mm with an unequivocal family

Results

One hundred forty-nine patients were included in the present study (92 men [62%]; age 47.4 ± 10.8 years; Table 1). The majority of them (85%) had severe dyspnea (New York Heart Association functional class III/IV). Syncope was present in 50 patients (34%). Forty-seven patients (32%) were complicated with hypertension. All subjects had significant LVOT obstruction (gradient ≥30 mm Hg), including 139 patients (93%) with obstruction at rest and the remaining 10 patients (7%) with latent

Discussion

In the present study, serum cTnI levels were elevated (≥0.04 ng/ml) in 28% of our patients. Both elevated cTnI and serum cTnI levels (as a continuous variable) were significantly associated with multiple parameters of disease severity, including LV hypertrophy (SWT, MWT, and LVMI), large left atrium (≥50 mm), and plasma levels of NT-proBNP. After adjusting for other variables, LVMI was independently associated with both elevated cTnI and serum cTnI levels, suggesting that LVMI was the major

Disclosures

The authors have no conflicts of interest to disclose.

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