Stability of radionuclide left ventricular volume measurements

Left ventricular volume measurements are useful in the evaluation of cardiac function and are important in the long-term management of patients with various cardiac diseases. Although there are many methods of measuring left ventricular volumes, a non invasive and reproducible method relies on radionuclide techniques. The errors in estimation of left ventricular volumes have previously been well studied. To date there is little information on the reproducibility of left ventricular volume measurements made by this technique at different points in time. This study evaluated 61 patients with stable coronary artery disease over a period of approximately 1 year. All patients had two resting radionuclide gated blood pool studies. Patients had no changes in symptoms, electrocardiographic findings or medication between studies. Using +/- 2 SD as 95% confidence limits for a true change, an end diastolic volume index change greater than -34 ml m-2 and +38 ml m-2 or an end systolic volume index change greater than -24 ml m-2 and +26 ml m-2 are required to state with confidence that a change has occurred between two examinations. These data provide guidelines to assess whether interval changes in left ventricular volumes are real or are due to variations within the technique.