Myocardial sympathetic nervous dysfunction detected with iodine-123-MIBG is associated with low heart rate variability after myocardial infarction.
The association between myocardial sympathetic innervation and heart rate variability after myocardial infarction was studied in a group of 12 men (aged 30-65 yr) 3 mo after their first myocardial infarction.


METHODS
Viable myocardium was imaged using 123I-phenylpentadecanoic acid (pPPA). Functioning myocardial sympathetic nervous tissue was imaged using [123I]-metaiodobenzylguanidine (MIBG). Heart rate variability was measured as the ratio of maximum-to-minimum RR intervals in ECG during deep breathing.


RESULTS
The patients were divided into normal (n = 6) and low (n = 6) heart rate variability groups. Myocardial infarction size (pPPA defect) was comparable in the normal and low heart rate variability groups. Even the MIBG defect size was not significantly different in the normal and low groups, the portion of viable myocardium with impaired sympathetic innervation (MIBG defect minus pPPA defect) was significantly greater in the low heart rate variability group than in the normal group.


CONCLUSIONS
The extent of viable myocardium with disturbed sympathetic innervation was greater in patients with low heart rate variability as compared to those with normal heart rate variability 3 mo after myocardial infarction.
Mäntysaari
M
M
Department of Clinical Physiology, Kuopio University Hospital, Finland.
Kuikka
J
J
Hartikainen
J
J
Mustonen
J
J
Mussalo
H
H
Tahvanainen
K
K
Länsimies
E
E
Uusitupa
M
M
Pyörälä
K
K
D019797:3-Iodobenzylguanidine; D000328:Adult; D000368:Aged; D004562:Electrocardiography; D006321:Heart / Q000000981:diagnostic imaging* / Q000294:innervation; D006339:Heart Rate; D006801:Humans; D007457:Iodine Radioisotopes; D007462:Iodobenzenes; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011877:Radionuclide Imaging; D013564:Sympathetic Nervous System / Q000503:physiopathology*
D007457:Iodine Radioisotopes; D007462:Iodobenzenes; D019797:3-Iodobenzylguanidine; C025391:omega-(4-iodophenyl)pentadecanoic acid