Changes in cardiac adrenergic nervous system after transmyocardial laser revascularisation assessed by I-123-MIBG SPECT. A preliminary report.
BACKGROUND
Metaiodobenzylguanidine (MIBG), a noradrenaline analogue which may be labelled with I-123, has been used in the assessment of pre-synaptic activity of the cardiac adrenergic nervous system (Syst(adren)) in several diseases. The effects of transmyocardial laser revascularisation (TMLR) on Syst(adren) have not yet been established.


OBJECTIVE
To examine whether TMLR-induced changes in Syst(adren) may be one of the mechanisms responsible for clinical improvement in patients undergoing this method of revascularisation.


METHODS
The study group consisted of 19 patients (mean age 63+/-9 years) who underwent TMLR, by using high-power CO(2) laser; as a single method of cardiac revascularisation. Syst(adren) was assessed before TMLR (STUDY-0), soon after the procedure (mean 13+/-5 days, STUDY-I), and in 12 patients six months after TMLR (STUDY-II). In total, 50 studies using I-123-MIBG SPECT were performed. The regional distribution of tracer was assessed qualitatively, using a 17-segment model of the left ventricle.


RESULTS
In 16% of examinations the assessment of the I-123-MIBG uptake was not possible due to the poor quality of images. Thus, 41 SPECT studies (16 - STUDY-0, 16 - STUDY-I, and 9 - STUDY-II) were analysed and compared. In STUDY-0, an impaired uptake of I-123-MIBG was found in 193 of 272 analysed segments. In STUDY-I, the I-123-MIBG uptake increased in 5% of defects (CI(0,95)=3-9%) and deteriorated in 55% (CI(0,95)=48-62%). When STUDY-II was compared with baseline, the uptake was increased in 25% of defects (CI(0,95)=17-34%) and decreased in further 25% of defects. When STUDY-II was compared with STUDY-I, the uptake increased in 67% (CI(0,95)=58-75%) of defects and did not deteriorate in any. The global MIBG uptake in STUDY-I decreased in 15 patients (94%, CI(0,95)=70-100%) when compared with baseline, and increased in all 9 patients with long-term follow-up data available, when STUDY-II to STUDY-I was compared.


CONCLUSIONS
TMLR significantly deteriorates Syst(adren) activity which, however, improves 6 months after the procedure to the values similar to those assessed pre-operatively. TMLR-induced impairment of Syst(adren) may contribute to the clinical improvement observed shortly (<6 months) after the procedure.
Nuclear Medicine Laboratory, National Institute of Cardiology, Warsaw, Poland.
Anna
A
Teresińska
Marian
M
Sliwiński
Stefania
S
Konieczna
Bozenna
B
Szumilak
Maria
M
Szymańska
Artur
A
Debski
Piotr
P
Hendzel
Zbigniew
Z
Juraszyński
D019797:3-Iodobenzylguanidine; D000328:Adult; D000368:Aged; D016342:Angioplasty, Laser / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006321:Heart / Q000294:innervation* / Q000528:radiation effects*; D006801:Humans; D053685:Laser Therapy; D008297:Male; D008875:Middle Aged; D009204:Myocardial Revascularization / Q000379:methods*; D019275:Radiopharmaceuticals; D013564:Sympathetic Nervous System / Q000528:radiation effects*; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon; D016896:Treatment Outcome
D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine