This study establishes the clinical value of the recently introduced handgrip-apexcardiographic test (HAT) as an additional tool for distinguishing exercise-induced diastolic abnormalities in coronary artery disease (CAD) patients from those in patients with hypertrophic cardiomyopathy (HCM). This stress test reliably assessing differences in diastolic indices during handgrip between 305 healthy volunteers and 39 patients with CAD without prior infarction as well as 17 patients with HCM showed two different patterns of handgrip-induced pathological changes in these indices. An 'ischemic diastolic response' was empirically defined by the presence of either a handgrip-induced more than doubling of a resting normal relative A wave to total height of the apex-cardiogram (ischemic compliance response) or a pathological prolongation of a resting normal total apexcardiographic relaxation time (ischemic relaxation response); whereas a 'nonischemic diastolic response' was defined by the presence of a positive HAT and by absence of the above-mentioned ischemic criteria. An ischemic pattern of diastolic abnormalities was present in 72% of CAD patients, whereas 94% of HCM patients showed a 'nonischemic' diastolic response. These results confirm that in CAD patients there is a typical response of diastolic apexcardiographic indices to isometric stress and, therefore, this simple stress test could be potentially useful in separating these patients from those with nonischemic myocardial disease states.