Caffeine and cardiac arrhythmias

Article Abstract:

Palpitations, the sensation of rapid, irregular of extra heartbeats, are often attributed to caffeine consumption. A review of the literature on the topic suggests that this is unsubstantiated by existing studies. One animal study demonstrated a reduction in the threshold for ventricular fibrillation, a dangerous type of arrhythmia, in dogs with acute myocardial infarction (heart attack) that are dosed with caffeine. However, the doses of caffeine were considerably higher than those generally ingested by humans. Another dog study showed no difference in ventricular fibrillation threshold in either caffeine or placebo fed dogs, but did show that adding five cigarettes a day (by tracheostomy) to the caffeine group lowered the ventricular fibrillation threshold. The effects of cigarettes alone were not studied. Human electrophysiologic studies suggest that caffeine does not affect the normal cardiac electric conduction system, but might aggravate preexisting rhythm disturbances. Another study of ventricular extrasystoles (isolated ectopic beats) with over 7,000 patients showed that those who consumed nine or more cups of coffee per day were twice as likely to experience ventricular extrasystole than those who drank three cups per day. However, it is unknown whether drinking more than nine cups per day is associated with a greater frequency of other coronary risk factors, such as smoking, obesity, and a sedentary lifestyle. Several studies of post-myocardial infarction patients showed no difference in the rate of cardiac arrhythmias in subjects given caffeine compared with those given placebo. In another study of patients with known ventricular irritability and malignant arrhythmias, caffeine was no more likely than placebo to induce those arrhythmias. Thus, moderate caffeine consumption has not been shown to increase the frequency of arrhythmias in normal subjects, patients with recent myocardial infarctions, or those with known ventricular arrhythmias. (Consumer Summary produced by Reliance Medical Information, Inc.)

Causes of, Caffeine, Arrhythmia, Heart conduction system

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Safety of calcium-channel blockers

Article Abstract:

Doctors should not prescribe short-acting calcium channel blockers until more research determines their safety. Calcium channel blockers are used to treat hypertension, chest pain caused by angina, and heart arrhythmias. Short-acting nifedipine, diltiazem and verapamil have all been linked to an increased risk of heart attack. Other diseases linked to short-acting calcium channel blockers include cancer and gastrointestinal hemorrhage. However, other researchers have not been able to confirm these results. Beta blockers, diuretics and ACE inhibitors can be used to treat hypertension and angina.

Calcium channel blockers

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Cardiovascular safety of COX-2 inhibitors

Article Abstract:

There is a possibility that COX-2 inhibitors cause abnormal blood clot formation, which could increase the risk of heart attack in patients who take them. More research is needed to confirm this finding.

Blood clotting disorders, Blood coagulation disorders, COX-2 inhibitors

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