Radioimmunoassay of plasma cyclic guanosine monophosphosphate level and its clinical implications as anew marker of heart failure

ABSTRACT

Plasma levels of cyclic guanosine monophosphate [cGMP] was determined by radioimmunoassay in 69 patients with heart failure due to various causes and in 15 healthy control subjects. Patients were classified according to functional New York Heart Association based on the left ventricular ejection fraction into 3 groups I [mild] II [moderate]. III [severe]. cGMP levels were significantly increased in the 3 groups compared to the control group [p<0.001]. The results were related to severity being significantly higher in each of group II and III than group I [p<0.001] and in group II than group I [p<0.05]. cGMP levels correlated negatively [r = 0.65, p < 0.05] with left ventricular ejection fraction but showed no significant correlation with age or sex [p > 0.05]. A statistical significant increase [p < 0.001] was detected after symptom limited exercise test in 10 patients with mild heart disease. Results of eighteen patients with severe heart failure who improved on treatment showed a statistical significant decrease in cGMP [p < 0.001] when compared with results on admission. The cut-off level of 4.9 nmol/L showed the maximum diagnostic sensitivity and specificity using the receiver operating characteristic curve. We conclude that cGMP can be used as a useful tool in evaluation of cardiac function and monitoring the response of therapy