The normal cardiac electrical system regulates both the heart rate and the heart rhythm. This article offers a brief explanation of the heart's electrical system and how it works.

Studies now show that smoking is the major cause of heart attacks in people under 40 years of age. Read what this means - for younger smokers, and for those not so young - here.

Amiodarone is the most powerful antiarrhythmic drug ever developed - but it is also the most toxic. In this article I describe this unique drug - its benefits, the risks, and how it should be used, here.

As expected, this week the United States Food and Drug Administration (FDA) approved dronedarone (Multaq, Sanofi-Aventis) for the treatment of atrial fibrillation. Dronedarone is thought to be a safer alternative for atrial fibrillation than its close cousin, amiodarone. The approval of the new drug largely rested on the results of the ATHENA trial, which demonstrated a significant reduction in the composite endpoint of death or hospitalization when dronedarone was compared to placebo.

There are some lingering questions with dronedarone, however. In another clinical trial, patients with significant heart failure actually had significantly increased mortality when this drug was used.

Accordingly, the new FDA indication for dronedarone specifies that the drug should be avoided in patients with significant heart failure.

You can read more about dronedarone here.