Effects of intravenous isradipine on left ventricular performance during rapid atrial pacing in coronary artery disease

Abstract

The effects of isradipine, a new dihydropyridine calcium antagonist, were evaluated in 24 patients referred for elective cardiac catheterization because of suspected coronary artery disease. Hemodynamics and left ventricular (LV) function (by digital subtraction angiography) were measured at baseline and during rapid atrial pacing (mean peak heart rate 135 beats/min), which induced chest pain or electrocardiographic changes in all patients. After a control pacing period, intravenous isradipine (0.01 mg/kg, n = 16) or placebo (n = 8) was administered in a double-blind fashion and all variables were measured again at baseline and during pacing to the same maximum heart rate. Before isradipine was given, pacing had no effect on systolic blood pressure, while increasing diastolic blood pressure (68 +/- 8 to 87 +/- 11 mm Hg, p less than 0.0001) and LV end-diastolic pressure measured in the immediate postpacing period (13 +/- 5 to 18 +/- 6 mm Hg, p less than 0.03) and decreasing LV end-diastolic volume index (59 +/- 18 to 40 +/- 12 ml/m2, p less than 0.001), stroke volume index (37 +/- 11 to 23 +/- 10 ml/m2, p less than 0.0001), ejection fraction (0.64 +/- 0.07 to 0.53 +/- 0.12, p less than 0.0003) and percent regional shortening in 4 of 5 myocardial wall segments. During pacing after isradipine, systolic and diastolic blood pressures were lower, ejection fraction was higher and percent regional shortening decreased in only 2 of 5 myocardial segments. In comparison to placebo, isradipine increased baseline heart rate, ejection fraction and stroke volume index while it decreased arterial pressure and end-systolic volume index before the second pacing period.(ABSTRACT TRUNCATED AT 250 WORDS)