This book introduces new ideas and concepts concerning cardiovascular disease,the most common cause of death worldwide. It aims to identify the relationship between the small variations on EKG- the simplest tool used to diagnose coronary artery disease (CAD)- and the presence of significant stenosis on the left anterior descending coronary artery or on the circumflex coronary artery. Furthermore,it treats the evolution of CAD overtime in Lebanese population,the new diagnostic tool of CAD: the coronary calcium score and its significant correlation with the presence or the absence of CAD, and the correlation between instent restenosis with the culprit coronary artery.