Burning tobacco is harmful to the heart and taking cocaine, but both effects are even more serious. In the United States, cardiologists from Dallas have conducted studies with 40 smokers with problems in the coronary arteries. After the burning of the cigar the diameter of the blood vessel was reduced by 5% and in each taking of cocaine it was reduced by 10%, but overall it has been observed that the reduction is 20%. This reduces the presence of oxygen in the myocardium and increases the risk of heart problems.