Abstract
Improved contractility after applying piroximone (PIR), the new phosphodiesterase-III
inhibitor drug, is difficult to prove clinically. However, augmented contractility
could increase the risk of myocardial ischemia when used in coronary artery disease
(CAD). The analysis of the end systolic pressure-volume relationship (ESPVR) as a
load-independent parameter of the contractile left ventricular (LV) function allows
for differentiation of PIR's effects: contractility vs unloading. We, therefore analyzed
ESPVR and LV function in 16 CAD patients before and after PIR, 0.75 mg/kg intravenously.
Emax increased by 39% (9/16 patients) and loops of the ESPVR (16 patients) moved leftward,
indicating improved contractility. The delta % changes PIR vs control (16 patients)
demonstrated augmentation of LV function via unloading: LV volumes decreased (ESV
by 37%, EDV by 19%), LV filling pressure by 34%, and systemic vascular resistance
by 19%; dP/dtmax increased by 28%, LV efficiency by 24%, cardiac index by 21%, and ejection fraction
by 13%. Pacing-induced anginal threshold increased by 47% after PIR and ischemic postpacing
LV filling pressure and ST segment changes tended to normalize under the drug's influence.
Thus, PIR improved LV function by both, unloading and positive inotropy. Lack of PIR-induced
angina and an increased anginal threshold indicate that the drug can be used safely
in CAD patients as well. The analysis of ESPVR proved to be safe and reliable in identifying
contractility during the diagnostic cardiac catheterization routine.
Abbreviations
AMI: Anterial myocardial infarction scar2 ): cardiac indexmax (mmHg/mL): slope k of the ESPVR
