The Quarterly Journal of Nuclear Medicine and Molecular Imaging 2004 March;48(1):20-5

Copyright © 2009 EDIZIONI MINERVA MEDICA

language: English

Sympathetic nervous function in patients with hypertrophic cardiomyopathy assessed by [123I]-MIBG: relationship with left ventricular perfusion and function

Pace L. ^{1, 2}, Betocchi S. ³, Losi M. A. ³, Della Morte A. M. ¹, Ciampi Q. ³, Nugnez R. ¹, Chiariello M. ³, Salvatore M. ^{1, 2}

¹ Department of Biomorphologic and Functional Sciences “Federico II” University, Naples, Italy 2 I.B.B. of National Council for Researches, Naples, Italy 3 Department of Medicine, Cardiovascular and Immunological Sciences “Federico II” University, Naples, Italy

Aim. The aim of the ­present ­study was to eval­u­ate
[123I] ­MIBG ­uptake and clear­ance in ­patients ­with hyper­troph­ic car­di­om­yo­pa­thy (HCM) and to ­assess ­their rela­tion­ships ­with ­left ven­tric­u­lar func­tion (sys­tol­ic and dia­stol­ic) and per­fu­sion.
Methods. Eleven con­sec­u­tive ­patients ­with HCM (8 men and 3 wom­en; ­mean age 38±12 ­years, ­none in the dilat­ed ­phase) under­went (in sep­ar­ate ­days, in ran­dom ­order) [123 I]-­MIBG scin­tig­ra­phy, [99mTc]-­MIBI ­SPET at ­rest, and ech­o­car­di­og­ra­phy. All ­patients ­were stud­ied in fast­ing con­di­tion, and all med­i­ca­tions ­were dis­con­tin­ued. [99mTc]-­MIBI ­SPET ­study was per­formed 1 ­hour ­after trac­er injec­tion. [123I]-­MIBG ­study was ­acquired 5 min­utes (pla­nar) and 4 ­hours (pla­nar and ­SPET) ­after the i.v. injec­tion of [123I]-­MIBG. Heart to med­i­as­ti­num ­ratio (H/M) was com­put­ed at 4 ­hours. Wash out ­rate (WOR) was com­put­ed as: (H ear­ly - H ­delayed)/(H ear­ly), ­after ­decay cor­rec­tion. Both [123I]-­MIBG and [99mTc]-­MIBI ­SPET ­were ana­lyzed on 3 ­short ­axis ­views (api­cal, mid­dle, and ­basal). Left ven­tric­u­lar out­flow ­tract gra­di­ent (LVOTG), ejec­tion frac­tion, vol­umes, sep­tum thick­ness, and ­left atri­al frac­tion­al short­en­ing (­LAFS) ­were eval­u­at­ed on ech­o­car­di­og­ra­phy.
Results. [123I]-­MIBG WOR ­showed a pos­i­tive rela­tion­ship ­with ­LVOTG (r=0.84, p<0.001) and sep­tum thick­ness (r=0.76, p<0.01), ­while a neg­a­tive one was ­found ­with ­LAFS (r=-0.66, p<0.05). The ­study ­group was divid­ed ­into: Group A (n=5) ­with high­er, and Group B (n=6) ­with low­er WOR ­than the ­median val­ue (i.e. 11%). Group A ­patients had sig­nif­i­cant­ly low­er ­LAFS (17.6±4.8 vs 26.8±7.2%, p<0.05), high­er ­LVOTG (49±35 vs 3±3 mmHg), and thick­er sep­tum (21±2 vs 17±2 mm) ­than Group B ­patients. Inferior and sep­tal ­wall [123I]-­MIBG ­uptake on 4 ­hour ­SPET was sig­nif­i­cant­ly low­er in Group A ­than in Group B. On the oth­er ­hand, no dif­fer­enc­es ­were ­found in 99mT-­MIBI ­SPET ­rest region­al ­uptake ­between the 2 sub­groups of ­patients.
Conclusion. These ­results sug­gest ­that car­diac sym­pa­thet­ic activ­ity cor­re­lates to car­diac anat­o­my (i.e. ­degree of hyper­tro­phy) and dia­stol­ic func­tion in ­patients ­with HCM.