Patients with chronic heart failure should not smoke, as smoking can enhance the excitability of the sympathetic nervous system. Increased excitability of the sympathetic nervous system releases norepinephrine, elevating norepinephrine levels. This can cause peripheral vasoconstriction, increase the afterload on the heart, and accelerate heart rate. Both of these effects can increase myocardial oxygen consumption. Furthermore, norepinephrine has a direct toxic effect on myocardial cells, promoting myocardial cell apoptosis and participating in the pathological process of ventricular remodeling. Moreover, excitement of the sympathetic nervous system can also enhance myocardial stress, potentially promoting the occurrence of arrhythmias. Therefore, patients with chronic heart failure should not smoke.