Heart Disease

A new study finds a link between having a fast, irregular heartbeat and the risk of developing heart disease, kidney disease, and death.

 

Heart arrhythmia is a condition where the heart beats quickly and at irregular intervals.  The most common form of arrhythmia is atrial fibrillation, where there is an irregular blood flow through the atria, the upper two chambers of the heart.

Blood flow through the heart is controlled by electrical signals. The brain sends impulses to the atria, instructing them to beat.  The signals make their way to the ventricles, the lower chambers of the heart, which push the blood through the body.  In atrial fibrillation, the upper chambers of the heart may not empty fully.  Blood may remain pooled in crevices of the atrium and a clot may form.  If the clot becomes loose, it will enter the bloodstream and may reach the brain where, if it restricts blood flow, it may cause a stroke.

The factors for developing atrial fibrillation include high blood pressure, diabetes, hyperthyroidism, having an abnormal structure of the heart, heart inflammation, underlying heart disease, excessive alcohol consumption and age.

Symptoms of atrial fibrillation include having a fast and irregular heartbeat, chest pain or pressure, shortness of breath, dizziness, sweating, nausea or fainting. Many people with atrial fibrillation experience no symptoms.  The condition is usually diagnosed by performing an electrocardiogram.

Previous research focused on heart arrhythmia and its associated risk of stroke.  Few other conditions have been examined for their link to atrial fibrillation.

A recent British Medical Journal study sought to quantify the association between atrial fibrillation and heart disease, kidney disease, and death. The authors examined over 100 studies involving 9 686 513 participants.  A statistical analysis between those with atrial fibrillation and outcomes of heart disease, kidney disease or death was performed and yielded the following results:

  • All-cause mortality: Sixty-four studies involving one million patients examined all-cause mortality.  Of the participants, 15% had atrial fibrillation. The relative risk of all-cause mortality was 1.46 and the absolute risk was 3.8 events/1000 participant years.
  • Cardiovascular mortality: Fourteen studies involving 342 453 patients examined cardiovascular mortality as an outcome. 5% of the adults had atrial fibrillation. The relative risk was 2.03 and the absolute risk increase was 2.6 events/1000 participant years.
  • Congestive heart failure: Six studies involving 82 476 patients, 15% of whom had atrial fibrillation, found that the relative risk of having congestive heart failure as an outcome was 4.9, or 11.1 events/1000 participant years.
  • Heart disease: Sixteen studies involving 395 957 patients examined heart disease as an outcome. There were 7.8% adults with atrial fibrillation, the relative risk was 1.61, and the absolute risk was 1.4 events/1000 participant years.
  • Chronic kidney disease and peripheral arterial disease: Three studies involving 467 000 patients, 4.3% with atrial fibrillation, examined kidney disease as an outcome and found the relative risk to be 1.64, with the absolute risk being 6.6 events/1000 participant years.
  • Stroke: Thirty-eight studies involving 6 143 925 adults assessed stroke incidents. There were 7.0% of adults with atrial fibrillation, the relative risk of having a stroke was 2.42 and the absolute risk was 3.6 events/1000 participant years.

The highest absolute risk increase was for heart failure, although atrial fibrillation was associated with an increased risk of all the outcomes examined. In patients with atrial fibrillation, kidney disease and mortality risks were at least as great as the risk of stroke.

The authors point out that the risks of developing cardiovascular and kidney disease in those with atrial fibrillation are the greatest in participants with a high baseline risk of cardiovascular disease.  The authors acknowledge that the mechanism by which atrial fibrillation is linked to an increased risk of cardiovascular and kidney disease is unclear.  They suggest that atrial arrhythmia treatment should include measures beyond stroke prevention.

 

 

 

Written By: Lynn Kim

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