A translational assessment of preclinical versus clinical tools for the measurement of cardiac contractility: comparison of LV dP/dt(max) with echocardiography in telemetry implanted beagle dogs.

Introduction: Regarding 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.

Methods: As 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/dt(max) (contractility measured as the maximum raise of pressure in the left ventricle) and LV dP/dt(max)/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.

Results: Both techniques demonstrated reproducible changes in contractility which showed a clear linear association. A change in LV dP/dt(max) of 1000 mmHg/s (in the range of 2500 to 7500 mmHg/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/dt(max)/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%.

Discussion: The 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.