EFFICACY OF LONG-TERM ADMINISTRATION OF TRANSDERMAL NITROGLYCERIN IN ASYMPTOMATIC PATIENTS WITH EFFORT-INDUCED SILENT-MYOCARDIAL-ISCHEMIA

The aim of our study was to investigate the effect of transdermal nitr oglycerin (NTG) on effort-induced silent myocardial ischemia in asympt omatic patients treated with beta-blockers or calcium antagonists. The acute effect was compared to two different schedules, continuous (24 h/day) or intermittent (16 h/day), of long-term administration. Ten as ymptomatic patients with coronary artery disease and a treadmill test positive for ischemia without angina were enrolled. Both acute (2 days ) and long-term (24 days) evaluations were conducted in a randomized, double-blind, crossover fashion. The ergometric parameters were collec ted on the 1st and the 2nd day of the acute phase (placebo and transde rmal NTG, respectively) and at the end of each 12-day period of long-t erm administration (continuous and intermittent, respectively). Transd ermal NTG administration acutely increased (p < 0.05) both time to 1-m m ST segment depression (451 +/- 43.2 vs. 374 +/- 24.1 s) and total ex ercise time (561.3 +/- 43.2 vs. 419.5 +/- 24.5 s). The acute efficacy was maintained over long-term treatment, regardless of the modality of administration. During continuous and intermittent patch application, time to 1-mm ST segment depression was 437.9 +/- 30.4 and 422 +/- 33. 4 s (p = NS vs. acute) and total exercise time was 498.8 +/- 30.4 and 495.1 +/- 33 s (p = NS vs. acute), respectively. Transdermal NTG incre ases, both acutely and chronically, exercise tolerance in asymptomatic patients with effort-induced silent myocardial ischemia. With the NTG dose we used, tolerance does not seem to be a problem over long-term administration.