Iodine-123 metaiodobenzylguanidine myocardial imaging in haemodialysed patients asymptomatic for coronary artery disease: a preliminary report.

AIM

The aim of this study was to evaluate the usefulness of iodine-123 metaiodobenzylguanidine (I-mIBG) myocardial scintigraphy in the detection of cardiac sympathetic neuropathy in haemodialysed patients without relevant cardiovascular symptoms.

MATERIALS AND METHODS

A group of 20 haemodialysed patients were examined. The stress/rest myocardial perfusion scintigraphy by gated single-photon emission computed tomography was performed. Cardiac sympathetic functions were evaluated by single-photon emission computed tomography and planar I-mIBG myocardial scintigraphy and also by 24-h Holter study, with heart rate variability (HRV) and signal-averaged electrocardiogram analysis of ventricular late potentials. Semiquantitative analysis of I-mIBG myocardial uptake was expressed as routine heart/mediastinum ratio (HMR) 15 [early (eHMR)] and 240 min [delayed (dHMR)] after administration and washout rate (WOR).

RESULTS

Myocardial perfusion scintigraphy showed normal values of all parameters, but semiquantitative I-mIBG cardiac imaging assessment indicated low values of HMR (eHMR 1.87±0.27; dHMR 1.74±0.25) and high values of WOR (31.38±9.49) compared with normal values. In 10 patients (50%) ventricular late potential was determined, and in these patients mean values of dHMR came up to 1.59±0.20. The mean value of HRV came up to 88.40±16.05 and significant correlations were found between HRV and eHMR (P=0.01) and dHMR (P=0.007).

CONCLUSION

I-mIBG scintigraphy can detect very early stages of cardiac sympathetic dysfunction. Low values of HMR and high values of WOR suggest an impaired cardiac adrenergic system in patients without any relevant symptoms of heart failure. Low values of HRV may confirm cardiac autonomic neuropathy.