How to design a clinical in cardiology. The main issues.

Accumulated clinical experience, arising from consecutive observation of patients, produces biased evaluations of drug efficacy. Only properly designed clinical trials can minimize bias and evaluate drug efficacy. However, clinical experience can be useful in clinical trial planning. The authors review the main aspects of the methodology of clinical trials in cardiology, namely the different phases of clinical research in humans, definition of the population, how to avoid bias, design and randomization options, determination of sample size, outcome types, and precautions to be taken during follow-up.