Because atrial hypertrophy is usually of minor degree, the ECG findings of atrial abnormality are more dependent on the duration of atrial contraction than on its amplitude. Likewise, the common increase in P-wave amplitude suggestive of right atrial hypertrophy or dilation (P pulmonade) often correlates poorly with clinical and anatomic findings—hence, the descriptive term, atrial abnormality. Prolongation and notching of P waves often indicate enlargement or delayed conduction within the atria, and these signs are helpful, but not diagnostic, in those conditions. Therefore, most electrocardiographers use the finding of atrial abnormality as an adjunct to the diagnosis of other conditions, such as rheumatic heart disease and left or right ventricular hypertrophy. Atrial enlargement may result in numerous arrhythmias, the most common being atrial fibrillation. There is some correlation between the amplitude of the fibrillatory waves and atrial size. Overall, the signs of atrial abnormality seem less important than other ECG criteria of abnormal size or function.