A roundup of breaking cardiac news

Cardiology Review® Online, April 2008, Volume 25, Issue 4

State of mind and state of health: another cardiovascular connection

Assessing patient quality of life (QOL) in the recovery period after sustained ventricular tachycardia or cardiac arrest provides helpful information on long-term survival, say authors of a study published in the March 2008 issue of HeartRhythm.

In this retrospective analysis, a subset of patients from the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial (n = 740) were followed for up to 2.5 years. Patients completed 3 QOL instruments at the trial's outset, self-reporting on general areas of health (ie, limitations in physical, emotional, or social functioning, bodily pain, vitality, and mental health) and cardiovascular-specific functioning. Cox regression models were constructed to examine the associations of QOL measures with survival time adjusted for age, gender, (white) race, index arrhythmia type (ventricular fibrillation/ventricular tachycardia), congestive heart failure (present per New York Heart Association (NYHA) class II-IV), ejection fraction, (non-sotalol) beta blocker usage (at hospital discharge), and therapy group (implantable cardioverter-defibrillator vs drug).

Surviving patients had significantly better scores in the more general QOL instrument, the SF-36 physical component, and univariately, this physical score was the strongest predictor of survival time. At 2 years, patients in the lowest tercile of the SF-36 physical summary score had the lowest survival (73%), compared with the middle (81%) and highest terciles (89%), respectively.

A press release announcing these results claims this is the first study to show how a patient's negative state of mind can have a direct impact on longterm survival after a cardiac event occurs. In that release, lead author Jonathan S. Steinberg, MD, chief of the Division of Cardiology, St. Luke's-Roosevelt Hospital Center, New York, notes that "in the days, months, and years after a patient has experienced an arrhythmic event, the psychosocial state of that individual may have an impact on the longevity of life or likelihood of lifethreatening arrhythmias." Therefore, "assessing a patient's mental well-being, and seeking counseling or therapy when needed, can be a critical factor in a successful recovery."

Heart

1. Steinberg JS, Joshi S, Schron EB, et al. Psychosocial status predicts mortality in patients with life-threatening ventricular arrhythmias. Rhythm. 2008;5:361-365.

Refined testing for common blood thinner

Following an August 2007 FDA-mandated change to warfarin labeling that alerted physicians that genetic testing may help to improve the initial dosing of this drug, the American Medical Association (AMA) and the Critical Path Institute announced an educational effort about this change on March 12, 2008.

The 2 groups collaborated on an educational brochure detailing how a patient's genetics influences their response to warfarin, and the genetic tests available to determine the best initial dose of the drug.

The educational effort is aimed at improving the safety and reducing the complications associated with warfarin's use, and is part of a larger, ongoing program to support personalized medicine.

Because warfarin's safe and effective dose varies greatly among patients, such information should prove useful in preventing comorbidities. Warfarin is the second most common drug, after insulin, implicated in emergency room visits for adverse drug events, especially bleeding complications.

In a press release announcing the program, James Rohack, MD, an AMA board member and cardiovascular disease specialist, noted that warfarin is "underutilized because of concerns about the risk of bleeding complications. Studies show that genetic factors explain why 40% of patients taking warfarin are more sensitive to the drug and require a smaller dose," he continued. "Genetic testing can identify patients at high risk for bleeding complications when warfarin is started, and allow the physician to use smaller doses to reduce the initial bleeding risk."

According to an AMA spokesperson, this genetic testing would be simpler than that for hereditary breast or colon cancer, which have multiple genetic mutations and which require packages that test for lots of different mutations. Because the warfarin test would really only be detecting mutations in 2 different genes (for now anyway, until more mutations that impact dosing are discovered), the pricing for the warfarin tests ranges from $100 to $500, depending on whether 1 or 2 genes are tested.

The brochure is available at

; mailed copies can be requested at:

www.ama-assn.org/go/warfarindosing pharmacogenomics@ama-assn.org

Heparin shows vein healing benefits in mice

A study on the effects of low-molecular-weight heparin (LMWH) in laboratory mice finds that in addition to preventing clots from forming, the drug may prevent existing clots from damaging delicate vein walls—and may accelerate healing of these clot-damaged vein walls.

Researchers, led by Peter Henke, MD, of the University of Michigan Medical School, cautioned that the results cannot immediately be translated into human patients, but that they do help illuminate the process by which LMWH works— including the potential advantages of pretreatment in at-risk patients, or early treatment of patients in whom a deep vein thrombosis (DVT) has formed.

Researchers surgically induced clots in mice, and studied how the size of the clot, the damage inflicted on the vein wall, and the natural repair process in the cells of the vein wall changed over time. Some of the mice received LMWH before the clot was formed, while others received it afterward. Another group of mice received no heparin. The experiment simulated DVT in humans.

In a press release announcing the findings, Dr Henke noted that "mice that received LMWH before their clot formed went on to experience a much faster and more complete healing process, compared with those that received LMWH only after the clot was formed and those that didn't receive the drug. And among those that received LMWH only after the clot was formed, the mice that got treated the soonest after clot formation healed the fastest and most completely."

Low-molecular-weight heparin is increasingly prescribed to hospitalized patients who might be at risk of developing DVT and pulmonary embolisms, especially older people, surgical patients, and people with a personal or family history of clotting problems. Deep vein thrombosis is especially likely to form in legs that are immobile for long periods of time, that have been injured, or that have poor circulation.

Although this research is not yet applicable to humans, the University of Michigan (U-M) Cardiovascular Center is taking other steps in the interim to improve clot care. Physicians at the Center are preparing to launch a new specialized Venous Disease Clinic for people with DVTs, or vein problems that might make them prone to DVTs. At the end of April, a new computerized tool will make it even easier for doctors, nurses, and physician assistants throughout U-M's 3 hospitals to evaluate patients for their risk of clots, and provide preventive care.

The Journal of Vascular Surgery

The study is published in the March issue of (2008;47[3]:616-624).

Dual-energy CT scan may have multiple uses

Circulation

Newly introduced imaging technology, dual-source computed tomography (DSCT), may eventually supplant other, more invasive diagnostic tests for myocardial ischemia, coronary artery disease, and other forms of heart disease. So hints a case study published in the March issue of the journal , which has been followed up by a study of 35 patients presented at the European Congress of Radiology in March 2008.

Traditionally, comprehensive diagnosis of coronary artery disease necessitated several imaging modalities, such as cardiac catheterization, nuclear medicine, or magnetic resonance scanners. This single-scan modality uses 2 x-ray spectrums to gain a static image of the coronary arteries and the heart muscle. The dual-energy approach enables mapping the blood distribution within the heart muscle and pinpointing areas with decreased blood supply.

According to a press release announcing the study, the technique can be completed in a single scan with one short breath-hold of approximately 15 seconds or less, and would provide costs savings and decrease radiation exposure for patients.

Cardiology Review

In a follow-up interview with , U. Joseph Schoepf, MD, noted that although this is fairly new technology, more than 300 of these units have been installed worldwide. These DSCT machines had previously been used in full body scans, and in imaging kidney stones, liver tumors, and tendons. The case represents the first use of the technology for cardiac imaging.

Dr Schoepf is clearly excited by the potential of this technology. Given current use of multiple diagnostic modalities and based on his 10 years of experience in cardiac imaging, Dr Schoepf hesitates to say that DSCT will provide "one-stop shopping" for imaging. But "this is as close as we'll get to a one-stop shop."

Circulation

The full case report is available in . 2008;117:1244-1245.

ICD study draws safety statement from Heart Rhythm Society

In an effort to head off confusion or anxiety among patients with implantable cardiac defibrillators (ICDs) following publication of a study outlining security and privacy concerns with the devices, the Heart Rhythm Society (HRS) released a statement on March 12 reiterating the importance and safety of ICDs.

The original study, titled "Pacemakers and implantable cardiac defibrillators: software radio attacks and zero-power defenses" discussed how technically adept computer scientists were able to intercept and capture signals sent from the implantable device. In addition to learning the patient name, date of birth, and medical identification number, the researchers were also able to "attack" the device, turning off therapy settings and making it produce a shock that could potentially induce a lethal arrhythmia.

Both the researchers and the HRS statement caution against generalizing from the study—the "attacks" were conducted from a distance of several centimeters, required specialized knowledge, and there are no known instances of such an attack. In addition, the researchers did not include technical details that would facilitate these attacks in their paper. Finally, although these attacks were intentional, "the risk of an inadvertent attack is low," said Kevin Fu, PhD, one of the authors of the study.

In the HRS press release, HRS President Bruce Lindsay, MD, pointed out that this was "a technical study that may be of interest to engineers who design wireless transmission systems," but that "the results do not have any important implications for patients and there is no reason for alarm." He continued, noting "this is not a product failure or safety recall. Millions of patients worldwide have benefited from the use of ICDs and this technology will continue to be critical in the treatment of patients who are at risk for life-threatening heart rhythm disorders."

IEEE Symposium on Security and Privacy

The study by Dr Fu and colleagues will appear in the proceedings of 2008 .

New Product News

The FDA granted tentative approval for a generic version of Cardiolite, the myocardial perfusion imaging agent used for detecting coronary artery disease. The generic version is manufactured by Covidien, and will be available pending final approval at the expiration of Cardiolite's period of marketing exclusivity on July 29, 2008.

The tentative FDA approval indicates that Covidien's Kit for the Preparation of Technetium Tc 99m Sestamibi Injection is safe and effective for use as recommended in the submitted labeling.

In a related story, Bristol-Myers Squibb Medical Imaging, the manufacturer of Cardiolite, as well as DEFINITY Vial for (Perflutren Lipid Microsphere) Injectable Suspension, and TechneLite (Technetium Tc99m Generator) has a new name—Lantheus Medical Imaging—and a new management team. This follows the December 2007 purchase of the company by Avista Capital Partners, a private equity firm, for approximately $525 million.