These observations then show that in one way or the other the heart was affected in 35 of 37 cases of rheumatic fever. The evidence was of three sorts; first, the duration of auriculoventricular conduction was increased, though not always, and usually not to the degree of causing heart block; second, alteration in the ventricular complex of the electrocardiogram affecting in certain instances the Q R S complex and in others either the interval between R wave and T wave, or the T wave itself; and third, the occurrence of numerous irregularities in cardiac rhythm.
These signs are characteristic of cardiac involvement, but are not specific for rheumatic fever; that is to say, from their presence rheumatic fever cannot be diagnosticated; all of them express merely derangement of the heart. They are signs which are, however, to be taken as evidence that the heart is affected by the rheumatic process even though an inference cannot be drawn as to the nature or the permanence of the injury. This may be slight and altogether transient even if the sign appears to be of advanced degree. The facts brought forward show that it is possible during the course of the disease to know whether the heart is involved in the general process. When sufficient data have been accumulated over a sufficiently long period of time, the usefulness for prognosis of observations like these will become established.