Objectives: To evaluate the effects of isradipine (ISR) and diltiazem (DIL) on exercise tolerance and ischemic ST depression in patients with stable effort angina.
Methods: Fourteen out-patients, 9 males and 5 females, aged 46-65 years (mean +/- SD = 57 +/- 8), with ischemic heart disease and reproducible ST-segment depression on two consecutive exercise stress tests in baseline conditions, underwent a study consisting of 4 periods: 1 and 3 placebo, 2 and 4 at random ISR (5 mg b.i.d.) and DIL (120 mg b.i.d.). At the end of each period a multistage treadmill exercise stress test (Bruce protocol) was performed.
Results: Both drugs significantly (p < 0.001) increased ischemia time (IT) (0.1 mV ST depression) as compared to placebo, from 438 +/- 132 s. to 620 +/- 164 s. (ISR) and 583 +/- 147 s. (DIL) without statistical difference between two drugs (p = 0.2), and significantly reduced (p < 0.002) the maximal ST depression, from -0.20 +/- 0.11 mV to -0.07 +/- 0.07 mV (ISR) and -0.09 +/- 0.11 mV (DIL). At the IT, systolic blood pressure increased (p = 0.02), from 180 +/- 19 mm Hg to 187 +/- 15 mm Hg (ISR) and 191 +/- 15 mm Hg (DIL); similarly, heart rate increased from 133 +/- 24 bpm to 144 +/- 18 bpm (ISR: p = 0.002) and 140 +/- 17 bpm (DIL: p = NS).
Conclusions: ISR and DIL, at the above dosage have showed an important and significant anti-ischemic effect (IT = +41.5% during ISR and +33.1% during DIL).