Heart News and Notes

Recent research finds that cardiac care guidelines, issued by the American College of Cardiology and the American Heart Association, are largely based on weak evidence. Nearly half rely on “expert opinion, case studies or clinical practice.” Less than 12 percent are backed by “multiple randomized trials or meta-analyses.”

That doesn’t mean they shouldn’t be used. They’re the best we have so far, but better focused studies are needed.

A study presented as an abstract at a meeting of the Society of Critical Care Medicine reported that hospitalized patients with sepsis (commonly known as blood poisoning) had a higher survival rate if they were taking statins when admitted. Another, presented to the Society of Thoracic Surgeons, reported that valve repair patients who were taking statins had a lower survival rate.

These are not peer-reviewed studies, and because they’re observational studies they don’t prove cause and effect.

How severe a heart attack is can be classified by chest pain, EKG evidence, and cardiac enzymes in the blood. A recent study of heart attacks from 1987 to 2002, in patients with no previous heart attack, found that their severity has been decreasing.

The declining death rate from heart attack has been attributed to better treatment. These results suggest that it might also be attributed to less severe heart attacks due to better preventive care.

Research published in BMC Medicine shows that for every second of pause in chest compressions during CPR there is a 1 percent reduction in the probability that heartbeat will be restored after defibrillation. This result supports the recommendation that compressions should not be interrupted for mouth to mouth breathing.

Which number is a better predictor of heart risk, systolic or diastolic blood pressure? Recent research says both together are better than either alone. Pulse pressure (the difference) is related to arterial stiffness, while mean arterial pressure (the average) is related to peripheral resistance to blood flow.

It should come as no surprise that injured tissues bleed. Now for the first time images have been captured by MRI, by using the magnetic properties of the iron in blood, that show bleeding inside the heart after a heart attack.

Recent research shows that such bleeding occurs in some patients after an artery is unblocked, when blood starts to flow again to injured heart tissue.

The amount of bleeding depends on the amount of damage, and patients who develop bleeding have a poorer chance of recovery.

Cardiogenic shock (CS), a complication of heart attack that occurs when the heart can’t supply enough blood to the organs, is the major cause of death in heart attack patients over 75. A study reported last month that even elderly patients with CS can benefit from prompt treatment with angioplasty and stents.

Another study confirmed that if treatment is delayed more than 12 hours after a heart attack begins, drugs are not only as effective as stenting, but cheaper.

For complex coronary artery blockages, CABG (coronary artery bypass grafting) was the “standard of care” when the alternative was bare metal stents. Early results from the SYNTAX study confirm that this is still true. Drug-coated stents give good results in low and intermediate risk cases, but in high-risk cases there are fewer problems after bypass surgery than after stenting.

Late in January the FDA (the federal Food and Drug Adminstration) announced that it is working with the makers of Plavix (clopidogrel) to investigate why it fails to inhibit blood clotting in an estimated 5 to 15 percent of patients. This “clopidogrel resistance” can lead to repeat heart attacks.

Recent studies, including one published last month, found a genetic variation in some people that prevents the conversion of clopidogrel (which does not itself affect clotting) to the active metabolite that inhibits platelet aggregation. Another study, in Canada, found that conversion to the active form can also be inhibited by PPIs (proton pump inhibitors, such as Nexium and Prevacid), which are often prescribed to prevent stomach irritation due to Plavix.

The FDA investigation aims not only to better quantify the effect but also to find better treatments, including antiplatelet drugs that don’t need to be converted and PPIs that don’t interfere with conversion.