Heart News and Notes

Phase one clinical testing of the use of adult cardiac stem cells to treat heart failure began on July 17 at Jewish Hospital in Louisville, KY. Stem cells, previously harvested from the patient’s own atrium and cultured in Boston, were injected into scar tissue in his damaged heart by means of a catheter through an artery in his leg. Because phase one trials test safety and feasibility, all test subjects will get the treatment.

Meanwhile, a research group in Boston is running animal tests on a method of growing new heart tissue without using stem cells. They say heart tissue, once believed unable to repair itself, slowly replaces about half the heart’s cells during one’s adult lifetime. Injecting a growth factor called neuregulin1 (NRG1) into a mouse’s heart speeds up the process, leading to improved function after the animal has had a heart attack.

Dietary recommendations issued three years ago by the American Heart Association suggested minimizing consumption of drinks with added sugar. Last month the AHA published a scientific statement online that set specific limits on total added sugar: 150 calories a day for men and 100 calories a day for women. Added sugar is sugar or syrup added to food either during processing or at the table; it has a greater effect on blood glucose and insulin than sugars that occur naturally in food. The average American consumes 355 calories a day of added sugar.

The AHA recommendation assumes that added sugar accounts for half the discretionary calories - the difference between the minimum to meet nutritional requirements and what’s needed to maintain weight. The other half is “solid fat.” But alcohol - at about 100 calories per standard drink, plus calories in the mixer - also counts in discretionary calories.

The food indusry isn’t listening. The New York Times on my breakfast table just before press time had a nearly full page ad for corn flakes with added honey.

Two studies in Germany and Switzerland, published last month in NEJM, independently identified new, more sensitive tests for troponins in the blood.

Troponins are cardiac enzymes that enter the blood when heart cells die, and detecting them indicates heart attack. But current test methods can take six to twelve hours to confirm a heart attack. The new tests can confirm a heart attack when a patient arrives at the emergency room.

The new tests cost no more than the existing tests and require no new equipment. Adopting them would mean that patients, maybe even you or I, could get quicker treatment for heart attack.

Atrial fibrillation (AF) - quivering of the upper chambers of the heart instead of beating - is the most common chronic arrhythmia. It carries a risk of stroke from clots that form when blood pools in the left atrial appendage. Patients with AF usually take warfarin (brand name: Coumadin) to prevent clots, but the dosage must be carefully regulated to avoid possibly fatal bleeding. A study published late last month suggested that warfarin should be used only in patients known to be at risk for stroke.

An article in The Lancet last month reported on a trial of a device to close off the left atrial appendage, implanted by catheterization without surgery. It proved at least as effective as warfarin in warding off stroke, but there were more complications. Later last month Mount Sinai Medical Center reported closing off the left atrial appendage by means of sutures, also by catheterization, in an AF patient who could not take warfarin.

At the European Society of Cardiology late last month, a report of a Phase III trial of an anticoagulant called dabigatran showed it to be more effective and safer than warfarin. If approved by the FDA it could become the new standard and eventually make warfarin obsolete.

Placement of automatic external defibrillators (AEDs) in public places is crucial in saving lives, according to two studies published in Circulation. A survey of 1710 American high schools equipped with AEDs found that out of 30 victims of cardiac arrest who received defibrillation, 20 survived to hospital discharge. A study in Copenhagen, Denmark, found that placement of AEDs depended on local or political initiatives instead of assessed cardiac risk, and that placement according to American Heart Association guidelines, rather than those of the European Resuscitation Council, covered more cases of cardiac arrest.

Location of body fat also turns out to be crucial. Studies have already shown that heart disease risk depends more on visceral fat (within the abdomen) than subcutaneous fat (in a layer under the skin). A new study reported late last month, based on two groups of 20 volunteers, found that markers of metabolic disorders, such as insulin sensitivity, depended on how much fat was in the liver.

Last month we reported, in an article on the Cochrane Reviews, that a metastudy found no advantage in treating blood pressure if it’s already below 140/90 (the criterion for hypertension). That finding was no boon to drug makers. So it’s no surprise that an industry-funded study published last month argued for targeting blood pressure to the lower level of 130 systolic, finding a reduced incidence of left ventricle hypertrophy (associated with heart failure and other problems).