A translational assessment of preclinical versus clinical tools for the measurement of cardiac contractility: Comparison of LV dP/dtmax with echocardiography in telemetry implanted beagle dogs

IntroductionRegarding evaluation of drug-induced changes in left ventricular contractility in safety pharmacology there is still a gap in knowledge between preclinically and clinically used measurements.MethodsAs a step towards translation of preclinical to clinical outcomes, this study in telemetered dogs was initiated to compare indexes of contractility, such as LV dP/dtmax (contractility measured as the maximum raise of pressure in the left ventricle) and LV dP/dtmax/P (contractility measured as the maximum raise of pressure in the left ventricle, corrected for pressure) (telemetry; both commonly preclinically used) and EF (ejection fraction) and FS (fractional shortening) (echocardiography; both commonly clinically used). Different inotropic states were induced by minoxidil, milrinone, isoprenaline, clonidine, atenolol and verapamil.ResultsBoth techniques demonstrated reproducible changes in contractility which showed a clear linear association. A change in LV dP/dtmax of 1000 mm Hg/s (in the range of 2500 to 7500 mm Hg/s; in healthy dogs) corresponded with a change in ejection fraction of approximately 7% and a fractional shortening of approximately 6%. A change of 10/s LV dP/dtmax/P (in the range of 35 to 85/s; in healthy dogs) corresponded with a change in ejection fraction of approximately 7% and a fractional shortening of 7%.DiscussionThe correlation found in this study could potentially enable a better - translational - assessment of the clinical relevance of changes in contractility indices measured with telemetry devices in preclinical safety studies.