Heart News and Notes

Last month saw a lot of studies related to the idea that hearts can heal themselves.

A study at Karolinska Institutet in Sweden measured the amount of carbon-14 in heart muscle cells. Because carbon-14 in the atmosphere spiked after cold war A-bomb tests, the amount contained in DNA depends on when the cell was formed. The study found that heart muscle cells are replaced at about one percent per year at age 25, slowing to about 0.45 percent at 75.

Several studies featured stem cells. Preliminary results from one study found that injecting stem cells released from a patient’s own bone marrow into heart muscle could relieve pain and improve exercise tolerance in severe intractible angina. Another found that treating a coronary artery with stem cells after heart attack and stenting resulted in improved blood flow. Still another, working with mice, found that treatment with stem cells, along with drugs to home the stem cells to where they’re needed, led to the formation of new arteries after heart attack.

In another study that reported success in animals and is now starting clinical trials, injecting a bioresorbable gel called B-1040 into damaged heart muscle provided temporary support for tissue repair. It doesn’t regenerate muscle but it results in a better functioning scar.

Another mouse study found that mice born without the enzyme GSNOR had more than the usual number of arteries and were immune to heart attack. If a coronary artery was blocked, blood went around the blockage. A different mouse study found that the protein TB-4, which is produced during embryonic development, could induce repair and regeneration in adult mice after heart attack.

Natural pacemanker activity is the subject of another ongoing study. Heart attacks can damage the heart’s internal pacemaker system, and the usual treatment is to implant an artificial pacemaker. The researchers, currently working with rats, are looking into genes that appear to improve the functioning of a damaged natural pacemaker.

All these results are preliminary, but they suggest that there may eventually be new ways to help a damaged heart to heal itself.

Research sponsored by the Lipton Institute of Tea found that the flavonoids in a cup a day of commercially available black tea can lower blood pressure and improve arterial elasticity, suggesting that tea might help prevent cardiovascular disease. Tea is the second most consumed drink in the world, after water, and is a major source of flavonoids in the diet.

Non-steroidal anti-inflammatory drugs, commonly called NSAIDs, are a first-line treatment for arthritis pain as well as pain from other causes. But they carry serious gastrointestinal (GI) risks (i.e., stomach and gut inflammation) and cardiovascular (CV) risks (e.g., heart attack).

A panel of experts convened by the Canadian Association of Gastroenterology voted on questions that led to an algorithm for NSAID use in patients with high CV or GI risk, assuming that patients at high CV risk take aspirin:

• Low risks: use NSAIDS.

• High CV risk: use naproxen.

• High GI risk: use a COX-2 inhibitor and a PPI (see below).

• Both risks high: prioritize carefully.

• Use NSAIDS at as low a dose for as short a time as possible.

Current guidelines recommend that heart patients who take Plavix (clopidogrel) to prevent blood clots after stenting should also take PPIs (proton pump inhibitors, long-acting antacids such as Nexium and Prevacid).

PPIs inhibit GI bleeding due to Plavix by reducing stomach acid. But (as we noted two months ago in these pages) PPIs can interfere with Plavix by inhibiting conversion to its active metabolite.

A study published last month suggests that only one PPI, omeprazole (Prilosec) interferes with Plavix. Two other PPIs tested, esomeprazole (Nexium) and pantoprazole (Protonix) showed no interference. The researchers did not test lansoprazole (Prevacid).

Lipoic acid is a powerful antioxidant found in small amounts in red meats and green leafy vegetables. Fed to rats as a dietary supplement, in a study published late in March, it lowered their triglycerides by an astounding 60 percent.

The researchers found that its mode of action is different from that of fibrate drugs used for the same purpose. Lipoic acid has already been used as a dietary supplement and is known to be safe.

Eprotirome is an experimental thyroid hormone analog that targets receptors in the liver that regulate uptake of cholesterol. In a clinical trial on patients who were already taking statins, reported April 1 at the American College of Cardiology meeting, it lowered LDL (bad cholesterol) by an additional 25 percent. Other thyroid hormone analogs with similar effects have had serious side effects, but eprotirome appears so far to be safe.