NITROGLYCERIN-AUGMENTED TL-201 REINJECTION ENHANCES DETECTION OF REVERSIBLE MYOCARDIAL HYPOPERFUSION - A RANDOMIZED, DOUBLE-BLIND, PARALLEL, PLACEBO-CONTROLLED TRIAL

Background Recent observations suggest that administration of nitrates before Tl-201 reinjection enhances the detection of reversible myocar dial hypoperfusion. Methods and Results Ninety-six patients who underw ent exercise-redistribution Tl-201 single photon emission computed tom ography (SPECT) and had persistent defects at 4-hour redistribution im aging were prospectively randomized into a double-blind protocol in wh ich they received a reinjection of Tl-201 (1.0 mCi) 5 minutes after ei ther placebo or 0.8 mg sublingual nitroglycerin administration, follow ed by repeat SPECT imaging. Of the 69 patients who had coronary angiog raphy, all except one had significant coronary stenoses. The overall e xtent of perfusion defect and the reversible component assessed by pol ar maps of the stress-redistribution images were similar in patients w ho received nitroglycerin or placebo. Among the 66 patients with persi stent defects in the redistribution images, 58% of those receiving nit roglycerin showed improved reversibility after reinjection, compared w ith 33% df patients receiving placebo (P<.05). Among 68 patients with significant coronary stenoses, those who received nitroglycerin and ha d coronary collateral circulation were more likely to exhibit improved reversibility after reinjection than the remaining patients (50% vers us 21%, P<.05). Moreover, the ratio of reversible to total defect in t he vascular territories supplied by collaterals was greater than or eq ual to 0.50 after reinjection in 80% of patients who received nitrogly cerin (n=20) compared with 40% of the patients who received placebo (n =15) (P<.05). Conclusions Nitrate-augmented Tl-201 reinjection signifi cantly, albeit modestly, improves detection of defect reversibility, e specially in patients with coronary collateral circulation.