Benefits of calcium channel blockers for patients with cardiovascular diseases

This meta-analysis combines the results of several studies that addressed the benefits of calcium channel blockers (CCBs) in treating cardiovascular conditions. CCBs were compared to other drugs for their ability to reduce the rate of death from any cause; death from cardiac disease; cardiovascular events (e.g. heart attack, stroke); and heart failure.  

Cardiovascular disease (CVD) refers to any disease that affects the heart and/or blood vessels (arteries and veins). This includes coronary artery disease (CAD), hypertension, diabetes and more.

CAD refers to a condition caused by the narrowing of blood vessels that supply the heart (the coronary arteries) due to fat deposits in the artery's wall. Most symptoms of CAD are the result of blood flow restriction that cannot meet the needs of the heart muscle. 

Calcium channel blockers (CCB) are a class of drugs that relax and widen blood vessels by affecting the muscle cells in the artery's wall. Some CCBs can also slow the heart rate, which can further reduce blood pressure and relieve chest pain (known as angina). CCBs are used as an additional treatment in patients with severe CAD or in patients who do not tolerate other drugs. The most often used drugs are amlodipine (Norvasc), diltiazem (Cardiazem) and verapamil (Isoptin).

The analysis involved 27 trials with overall 175,634 participants with cardiovascular diseases. 78,240 patients were assigned to recieve CCBs while the remaining 97,394 were put on non-CCB drugs or placebo (a substance with no therapeutic effect). 

Alltogether, results showed that CCBs reduced the rate of stroke compared to placebo or another commonly used class of drugs, ACE inhibitors. Some CCBs (those used to reduce blood pressure) demonstrated a better control of all-cause deaths. The risk of major cardiovascular events (i.e. heart attacks) was almost similar for CCB and non-CCB drugs. However, CCBs increased the risk of heart failure (weakness and reduced functionality of the heart) as compared with other commonly used medications.

In summary, CCBs did not show superiority over other drugs in preventing cardiac-related deaths or major cardiovascular events, and actually increased the risk of heart failure. On the other hand, CCBs were able to reduce the risk of strokes (both fatal and nonfatal) in CVD patients. 

The benefit of CCB may vary substantially between different cardiovascular diseases. This class of drugs is more beneficial for hypertension, while it is less frequently used for treating CAD or diabetes. The present analysis comprises a very heterogeneous group of patients, having various cardiovascular diseases. Large meta-analyses that will test CCBs for each CVD individaully is required in order to draw disease-specific conclusions.

In addition, the authors did not make a distinction between the two major types of stroke, hemorrhagic (due to bleeding) and ischemic (due to blockage of blood supply to the brain). It is unclear what types of stroke were prevented, and by which subtype of CCBs.