Power of the Cluster

The past 50 years have witnessed sea changes in cardiovascular medicine and research.1 We came to recognize untreated hypertension as a highly malignant disorder and to recognize that medical treatment of hypertension leads to marked reductions in risk of stroke, myocardial infarction, and premature death. We also came to recognize the power of the randomized trial for assessing candidate strategies for prevention and treatment. Indeed, mega-trials conducted by cardiovascular clinician scientists have played a critical role in defining nearly every major evidence-based intervention, from hypertension treatment to cholesterol reduction and use of aspirin.1