Molecular imaging for efficacy of pharmacologic intervention in myocardial remodeling

SWM van den Borne, S Isobe, HR Zandbergen… - JACC: Cardiovascular …, 2009 - jacc.org
SWM van den Borne, S Isobe, HR Zandbergen, P Li, A Petrov, ND Wong, S Fujimoto…
JACC: Cardiovascular Imaging, 2009jacc.org
Objectives: Using molecular imaging techniques, we examined interstitial alterations during
postmyocardial infarction (MI) remodeling and assessed the efficacy of antiangiotensin and
antimineralocorticoid intervention, alone and in combination. Background: The antagonists
of the renin-angiotensin-aldosterone axis restrict myocardial fibrosis and cardiac remodeling
after MI and contribute to improved survival. Radionuclide imaging with technetium-99m–
labeled Cy5. 5 RGD imaging peptide (CRIP) targets myofibroblasts and indirectly allows …
Objectives
Using molecular imaging techniques, we examined interstitial alterations during postmyocardial infarction (MI) remodeling and assessed the efficacy of antiangiotensin and antimineralocorticoid intervention, alone and in combination.
Background
The antagonists of the renin-angiotensin-aldosterone axis restrict myocardial fibrosis and cardiac remodeling after MI and contribute to improved survival. Radionuclide imaging with technetium-99m–labeled Cy5.5 RGD imaging peptide (CRIP) targets myofibroblasts and indirectly allows monitoring of the extent of collagen deposition post-MI.
Methods
CRIP was intravenously administered for gamma imaging after 4 weeks of MI in 63 Swiss-Webster mice and in 6 unmanipulated mice. Of 63 animals, 50 were treated with captopril (C), losartan (L), spironolactone (S) alone, or in combination (CL, SC, SL, and SCL), 8 mice received no treatment. Echocardiography was performed for assessment of cardiac remodeling. Hearts were characterized histopathologically for the presence of myofibroblasts and thick and thin collagen fiber deposition.
Results
Acute MI size was similar in all groups. The quantitative CRIP percent injected dose per gram uptake was greatest in the infarct area of untreated control mice (2.30 ± 0.14%) and decreased significantly in animals treated with 1 agent (C, L, or S; 1.71 ± 0.35%; p = 0.0002). The addition of 2 (CL, SC, or SL 1.31 ± 0.40%; p < 0.0001) or 3 agents (SCL; 1.16 ± 0.26%; p < 0.0001) demonstrated further reduction in tracer uptake. The decrease in echocardiographic left ventricular function, strain and rotation parameters, as well as histologically verified deposition of thin collagen fibers, was significantly reduced in treatment groups and correlated with CRIP uptake.
Conclusions
Radiolabeled CRIP allows for the evaluation of the efficacy of neurohumoral antagonists after MI and reconfirms superiority of combination therapy. If proven clinically, molecular imaging of the myocardial healing process may help plan an optimal treatment for patients susceptible to heart failure.
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