Cardiac involvement in cystic fibrosis evaluated using cardiopulmonary magnetic resonance

Abstract

Cystic fibrosis (CF) transmembrane conductance regulator is expressed in myocardium, but cardiac involvement in CF remains poorly understood. The recent development of a combined cardiopulmonary magnetic resonance imaging technology allows for a simultaneous interrogation of cardiac and pulmonary structure and function. The aim of this study was to investigate myocardial manifestations in adults with CF, both in a stable state and during an acute respiratory exacerbation, and to investigate the relationship between cardiac and pulmonary disease. Healthy adult volunteers (n = 12) and adults with CF (n = 10) were studied using a multiparametric cardiopulmonary magnetic resonance protocol. CF patients were scanned during an acute respiratory exacerbation and re-scanned when stable. Stable CF was associated with left ventricular dilatation and hypertrophy (LVH; left ventricular mass: CF 59 ± 9 g/m² vs. control 50 ± 8 g/m²; p = 0.028). LVH was predominantly driven by extracellular myocardial matrix expansion (extracellular matrix mass: CF 27.5 ± 3.4 g vs. control 23.6 ± 5.2 g; p = 0.006; extracellular volume [ECV]: CF 27.6 [24.7-29.8]% vs. control 24.8 [22.9-26.0]%; p = 0.030). Acute CF was associated with an acute reduction in left ventricular function (ejection fraction: acute 57 ± 3% vs. stable 61 ± 5%; p = 0.025) and there was a suggestion of myocardial oedema. Myocardial oedema severity was strongly associated with the severity of airflow limitation (r = - 0.726, p = 0.017). Multiparametric cardiopulmonary magnetic resonance technology allows for a simultaneous interrogation of cardiac and pulmonary structure and function. Stable CF is associated with adverse myocardial remodelling, including left ventricular systolic dilatation and hypertrophy, driven by myocardial fibrosis. CF exacerbation is associated with acute myocardial contractile dysfunction. There is also a suggestion of myocardial oedema in the acute period which is related to pulmonary disease severity.

Keywords: Cardiac magnetic resonance; Cystic fibrosis; Myocardial fibrosis; Myocardial inflammation; Parametric mapping.

Fig. 1

Changes in cardiac structure and function between acute respiratory exacerbation and stable period. There was a reduction in myocardial capillary permeability (K^trans; min⁻¹) between acute respiratory exacerbation and stable stage. Likely as a result, myocardial extracellular volume (ECV; %) and T1 relaxation (ms) time both reduced, in keeping with a reduction in myocardial oedema. In turn, left and right ventricular contractile function improved (LVEF left ventricular ejection fraction; %; RVEF right ventricular ejection fraction; %)

Fig. 2

Myocardial tissue characterisation in cystic fibrosis. Representative endocardial and epicardial regions of interest for T1 and T2 mapping are shown. Mid third of the left ventricle (LV) wall was used for analysis. A Inferior right ventricle insertion point late enhancement (arrow). B Mid LV T2 mapping (T2 = 46 ms). C Mid LV native T1 mapping (T1 = 1088 ms). D Mid LV post contrast T1 mapping (post contrast T1 = 588 ms). E, F Long axis cine imaging showing the position of mid LV short axis parametric mapping slices

Fig. 3

Relationship between myocardial and pulmonary tissue characteristics and percentage of predicted normal forced expiratory volume in one second (FEV₁%). In acutely exacerbating cystic fibrosis patients, a myocardial T1 relaxation time and b myocardial extracellular volume (ECV), both indicative of myocardial oedema, showed strong negative correlations with FEV₁%. c Pulmonary T1 relaxation time was strongly correlated with FEV₁%

Fig. 4

Pulmonary tissue blood flow maps. a, b Right lung in patients with cystic fibrosis. There is a visible reduction in pulmonary tissue blood flow in right upper lobes (arrows). c, d Right lung in healthy controls