One more reason, especially for heart patients to quit smoking: Heart patients who had implanted defibrillators and also smoked were seven times more likely to have the devices jolt their hearts back into normal rhythm than nonsmokers with the devices, as shown by a study conducted at Washington University School of Medicine in St. Louis.

Implantable cardioverter-defibrillators (ICDs) are self-contained units that are placed within the chest to monitor heart rhythms and deliver electrical charges directly to heart muscle to correct abnormal rhythms. Abnormal rhythms can occur without warning, and some can cause death rapidly if no action is taken. A recent study demonstrated that ICDs decreased the risk of death by 23 percent in patients with congestive heart failure.

"ICDs are implanted in patients at high risk for sudden cardiac death," Sánchez says. "The devices shock the heart out of dangerous rhythms within seconds after they detect them. It's like having a little ambulance in your chest."

Analysis of the study showed that current smoking generated a seven-fold increased risk for ICD discharge in heart patients.

The researchers warned that smoking can harm the heart in several ways:

1) nicotine increases the amount of adrenaline, which can lead to blood vessel constriction and decreased blood flow to the heart
2) smoking increases blood clotting factors, which can raise the chance of blood vessel blockage
3) smoking increases blood clotting factors, which can raise the chance of blood vessel blockage

Anyone of the above can result to imbalanced oxygen supply compared to the amount of oxygen needed by the heart. Such oxygen deficiency will lead the heart to dangerous rhythms.

Indeed it is difficult to quit smoking (believe me, I know!). Heart patients (and normal people) know it is harmful but still they smoke. But if we are thinking in the lines of heart disease and other serious conditions related to smoking, then quitting should be advocated for tons of these reasons.

Read more at WUSTL School of Medicine News.