Diagnostic value of the apex beat.

100 patients were examined without knowledge of other findings to assess the value of apex displacement as a sign of cardiomegaly; 25 had a radiographic cardiothoracic ratio greater than 50%. The apex was located in only half of the patients, palpability being influenced by frame size, percentage ideal body weight, and percentage body fat. By comparison with the cardiothoracic ratio, apex displacement beyond the midclavicular line as the diagnostic test for cardiomegaly had a specificity of 76%, a sensitivity of 59%, a positive predictive value of 59.4%, and a negative predictive value of 76.9%. Another clinical sign of cardiomegaly, apex more than 10 cm from the midsternal line, was more sensitive but even less specific.