Myocardial delayed enhancement by magnetic resonance imaging in patients with Chagas' disease: a marker of disease severity.
OBJECTIVE
We sought to investigate whether myocardial delayed enhancement (MDE) by magnetic resonance imaging (MRI) could quantify myocardial fibrosis (MF) in patients with Chagas' heart disease (CHD), thus defining the severity of the disease.


BACKGROUND
Myocardial fibrosis secondary to ischemic disease can be imaged using MDE. Advanced CHD is characterized by progressive MF.


METHODS
Fifty-one patients with CHD were enrolled: 15 seropositive asymptomatic participants in the indeterminate phase (IND); 26 patients with known clinical CHD; and 10 patients with known CHD and ventricular tachycardia (VT). Using a 1.5-T MRI system, we acquired left ventricular (LV) short-axis slices using cine-MRI (LV function) and inversion-recovery gradient-echo (MDE).


RESULTS
Myocardial fibrosis by MRI was present in 68.6% of all patients, in 20% of IND, 84.6% of CHD, and 100% of VT (p < 0.001). Quantified MF increased progressively across disease severity subgroups (0.9 +/- 2.3% in IND; 16.0 +/- 12.3% in CHD; and 25.4 +/- 9.8% in VT, p < 0.001) and New York Heart Association functional classes (I: 7.5 +/- 9.5%; II: 21.9 +/- 13.8%; and III: 25.3 +/- 9.9% of LV mass, p < 0.001). Left ventricular ejection fraction and MF had significant negative correlation (r = -0.78, p < 0.001), similar to the segmental MF and function: 4.9 +/- 15.1% of MF in normal function, 32.5 +/- 32.5% in mildly hypokinetic, 57.8 +/- 31.4% in severely hypokinetic, and 72.3 +/- 36.2% in akinetic and dyskinetic segments, respectively (p < 0.001).


CONCLUSIONS
In CHD, MDE by MRI quantifies MF that not only can be detected in the early asymptomatic stages but parallels well-established prognostic factors and provides unique information for clinical disease staging.
Rochitte
Carlos E
CE
Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil. rochitte@incor.usp.br
Oliveira
Paulo F
PF
Andrade
Joalbo M
JM
Ianni
Bárbara M
BM
Parga
José R
JR
Avila
Luiz F
LF
Kalil-Filho
Roberto
R
Mady
Charles
C
Meneghetti
José C
JC
Lima
João A C
JA
Ramires
José A F
JA
D002598:Chagas Cardiomyopathy / Q000150:complications / Q000473:pathology*; D005260:Female; D005355:Fibrosis; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009206:Myocardium / Q000473:pathology; D012720:Severity of Illness Index