There has been nothing on this subject at book length--one which usually meets with mutual doctor-patient embarrassment and an unenlightening ""Take it easy"" at the end of a coronary incident. Brenton, a reliable researcher, has used what suggestive but not conclusive scientific studies exist--the most specific being a Japanese analysis of la mort d'amour. It is however possible to establish that sexual activity promotes the highest heart rate; that psychological and emotional stress accelerate cardiac conditions; that the individual's general fitness often determines his maintenance of a normal or reduced sexual regimen. Specific symptoms and hazards are indicated, and there's a chapter for the pregnant woman with a cardiac liability although most of this is directed toward the middle-aged-and-over male. They will find Mr. Brenton much more helpful than Peter Steincrohn.