Effect of pharmacologic therapy on angina frequency, ST segment depression during ambulatory ECG monitoring, and treadmill performance in patients with chronic stable mild angina

Abstract

Fifteen patients aged 55 ± 6 years (mean ± SD) with mild, chronic stable angina were evaluated after 2 weeks of sublingual nitroglycerin therapy (control) and also after 12 weeks of treatment with either propranolol, up to 320 mg per day, or nifedipine, up to 120 mg per day, in order to measure signs of ischemia and the response of symptoms to therapy. Compared with the control period, there was a decrease in average daily episodes of angina from 1.0 ± 0.8 to 0.5 ± 0.4 with treatment ( p = 0.10). There was a significant decrease of ≥ 1.0 mm ST segment depression (both symptomatic and asymptomatic), from 6.1 ± 6.5 to 1.5 ± 2.4 episodes per 24 hours, p < 0.001, and of asymptomatic episodes of ST segment depression, from 3.5 ± 3.9 to 1.0 ± 2.1 episodes per 24 hours, p = 0.03. The number of patients who had any episodes of ≥ 1.0 mm ST segment depression on their 24-hour ECG decreased from 14 to 6 (93% to 40% of patients, p = 0.005) with treatment, and the number of patients with any episodes of ST segment depression without symptoms decreased from 11 to 5 (73% to 33% of patients, p = 0.07). There was an insignificant increase in treadmill time from 333 ± 134 to 380 ± 156 seconds, and an insignificant decrease in maximum double-product from 16,631 ± 3,599 to 14,922 ± 4,086; the number of patients with angina at maximum exercise decreased from 13 to 10 (87% to 67%). It can therefore be concluded that patients with mild, chronic stable angina have a low rate of both symptomatic and asymptomatic ST segment depression on 24-hour ECG; the frequency of both was greatly reduced with pharmacologic therapy and the incidence of silent ischemia (asymptomatic transient ST segment depression) was eliminated in 67% of patients during pharmacologic treatment, even though performance on exercise treadmill testing was not greatly improved.