Myocardial perfusion quantification in patients suspected of cardiac syndrome X with positive and negative exercise testing: a [13N]ammonia positron emission tomography study.
BACKGROUND
The combination of angina pectoris, angiographically normal coronary arteries, and a positive exercise stress test (EST) is referred to as cardiac syndrome X. However, a large group of patients suspected of syndrome X reveals a normal exercise stress test and weakens the diagnosis of syndrome X. Previous studies demonstrated an impaired coronary flow reserve on ammonia positron emission tomography (PET) in patients with syndrome X.


OBJECTIVE
To evaluate the coronary flow reserve in patients suspected of syndrome X with positive and negative EST findings, using [(13)N]ammonia PET as the diagnostic aid.


METHODS
Forty-two patients with chest pain and a normal coronary angiography, were analysed by exercise stress testing (EST) and the dypyridamole stress test (DST) on [(13)N]ammonia PET. Two subgroups were predefined, based on outcome of EST: an EST positive and negative group. A normal control group was used as the reference method.


RESULTS
A total of 24 (57%) out of 42 patients had significant ST-T changes (EST positive). [(13)N]ammonia PET showed a significantly lower rest flow in the EST positive and EST negative group compared to controls (P<0.001 and P=0.0028, respectively). DST [(13)N]ammonia PET perfusion was significantly reduced in flow in both the EST positive and EST negative groups (P<0.001 both), as was the DST/rest [(13)N]ammonia perfusion reserve (P<0.001 for both), compared to normal controls.


CONCLUSIONS
PET demonstrates a reduced coronary flow reserve in patients suspected of syndrome X, irrespective of the EST findings.
de Vries
Jessica
J
Faculty of Medicine, University Medical Center Groningen and University of Groningen, the Netherlands.
DeJongste
Mike J L
MJ
Jessurun
Gillian A J
GA
Jager
Pieter L
PL
Staal
Michiel J
MJ
Slart
Riemer H J A
RH
D000328:Adult; D000641:Ammonia / Q000378:metabolism* / Q000494:pharmacology*; D003952:Diagnostic Imaging / Q000379:methods*; D004176:Dipyridamole / Q000494:pharmacology; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D017566:Microvascular Angina / Q000175:diagnosis* / Q000473:pathology*; D008875:Middle Aged; D009590:Nitrogen Radioisotopes / Q000627:therapeutic use*; D010477:Perfusion; D049268:Positron-Emission Tomography / Q000379:methods*
D009590:Nitrogen Radioisotopes; D004176:Dipyridamole; D000641:Ammonia