Why is it that cardiovascular disease is the main cause of death in modern societies?

Several reasons: Several factors that involve increase prevalence of atherosclerosis including increase stress, high blood pressure , diabetes, high cholesterol , fast food diet , sedentary life stool with decrease excercise, more control of infections which kills more people in third world countries.

Several: Almost no tuberculosis, no small pox, other treatable infections. Curable leukemias and many tumors. Rare starvation and many efforts to reduce or salvage trauma patients. So heart and stroke are number one and three in our time with numerous bad choices: smoking, obesity, terrible diets and sedentary life.Diabetes is almost 1/3 of our population and prone to atherosclerosis.