Estimations of serum lipids and lipoprotein patterns were made in 32 patients with an abnormal repsonse to an atrial pacing test, and compared with similar estimations in 32 patients giving a normal response to the atrial pacing test. The frequency of serum lipid abnormalities was not significantly different in the two groups. These results were compared with the reported nature and frequency of lipid and lipoprotein abnormalities in patients with angiographically proved coronary artery disease, and the implications of these results are discussed
