Ventricular muscarinic receptor remodeling in patients with and without primary ventricular fibrillation. An imaging study |
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Authors: | Alejandro N Mazzadi PhD Julien Pineau MD Nicolas Costes PhD Didier Le Bars PhD Fréderic Bonnefoi BSc Rapha?l Porcher PhD Pierre Croisille MD PhD Philippe Chevalier MD PhD |
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Institution: | 1. CERMEP-Imagerie du Vivant, Lyon, France 5. CESyMA, ECyT, Universidad Nacional de General San Mart??n, Buenos Aires, Argentina 2. HCL (H?spices Civils de Lyon), Lyon, France 3. UCBL (Universit?? Claude Bernard), Lyon, France 4. D??partement de Biostatistique et Informatique M??dicale, H?pital Saint-Louis, Paris, France 6. Service de Cardiologie, H?pital Cardiovasculaire et Pneumologique Louis Pradel, BP Lyon Montchat, 69677, Bron Cedex, France
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Abstract: | Background Vagal innervation modulates the electrical stability of the left ventricle (LV) during ischemia. Thus, abnormal parasympathetic activity in myocardial infarction (MI) patients with primary ventricular fibrillation (FV) can account for their arrhythmic disorders. We evaluated LV muscarinic receptor density (B max) after MI in patients with (FVG, n?=?11) or without (nFVG, n?=?12) primary FV. Methods and Results The B max was measured by positron emission tomography and the specific antagonist 11C]methylquinuclidinyl benzilate (11C]MQNB) in 23 patients 39?±?19?days post-MI, and 10 volunteers. Myocardial damage was quantified by delayed contrast-enhanced magnetic resonance imaging. Three short-axis slices per subject were analyzed and six time-activity curves per slice were fitted to a 3-compartment ligand-receptor model. The B max in remote regions of the 23 patients (67?±?36?pmol/mL?·?tissue; n?=?139) was higher than in normal regions of volunteers (33?±?16?pmol/mL?·?tissue; n?=?171; P?=?.01). Receptor density in remote regions was similarly upregulated in nFVG (69?±?31?pmol/mL?·?tissue, n?=?73) and FVG (66?±?40?pmol/mL?·?tissue, n?=?66; P?=?.72). In damaged regions, the B max was reduced in both patient groups (44?pmol/mL?·?tissue). Conclusions Chronically infarcted patients with or without primary FV share similar patterns of ventricular muscarinic receptor remodeling, characterized by receptor upregulation, in remote non-damaged territories. |
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