Bacterial endocarditis. A changing disease.
Sixty-eight acceptable cases of bacterial endocarditis were obtained from hospital records for the 20-year period 1945 to 1964 inclusive.

Cases were classified according to age, nature of any underlying heart disease, and type of infecting organisms. Two main groups emerged with a very significant mean age difference; the younger were patients with chronic rheumatic heart disease, and a preponderance of Streptococcus viridans infection, while the older very often had no clear antecedent heart disease at all, and were infected predominantly with organisms more virulent than Streptococcus viridaus .

Comparison of these two main groups over the 20-year period showed that the disease was occurring progressively more commonly in older patients without antecedent heart disease.

Analysis of the Registrar General's statistics for deaths from bacterial endocarditis for the same period shows a progressively rising mean age, and a steadily increasing percentage of deaths in the over 60's. This trend has continued despite a stable over-all mortality since 1954, suggesting a real increased incidence of the disease in the older age-groups.

It is concluded that a change in the pattern of bacterial endocarditis has occurred. Possible factors involved in this change are discussed, and its clinical implications stressed.