Scientists have confirmed that regular physical activity is associated with a lower risk of cardiovascular disease, dementia, all-cause disability and other health problems. However, few studies have looked at the possible association between time spent sitting and mortality. The two are not exact opposites, since a person who gets a good 30-minute work-out every day and then sits in front of a computer screen for 8 hours has high levels of both physical activity and sedentary behavior.

A new study by Emmanuel Stamatakis and colleagues at University College London has addressed the gap, and the results suggest that too much time spent in front of a computer or the TV increases the risk cardiovascular events and all-cause mortality, even in people also happen to engage in regular exercise.

To reach these troubling conclusions, Stamatakis’ group reviewed data from 4,500 respondents to the Scottish Health Survey of 2003. Participants were 35 years old or older, and were followed for at least 4 years.

Respondents were asked describe the time spent per day engaged in screen-based entertainment (like watching TV or surfing the Internet).

After adjusting for age, gender, BMI, ethnicity, social class, cigarette smoking and other factors, Stamatakis’ group determined that cardiovascular risk was about 50% higher among respondents who engaged in screen-based entertainment for two or more hours per day. They also found that all-cause mortality was more than twice as high among those who engaged in four or more hours of the same.

Importantly, when the scientists adjusted their analysis to account for physical activity, they found no appreciable reduction of the risk associated with sedentary behavior.

In an effort to study physiological mechanisms underlying the link between excessive sedentary behavior and cardiovascular risk, Stamatakis’ team looked at a subset of respondents for whom blood test results were available. (more…)

Multaq, an expensive new drug for the treatment of atrial fibrillation, is only half as effective as amiodarone, its generic congener, and it has a similar side-effect profile according to Sanjay Kaul and colleagues at Cedars-Sinai Medical Center.

As a result Multaq should be reserved for patients in whom amiodarone is ineffective or associated with intolerable side-effects, the scientists concluded in an op-ed piece in the Journal of the American College of Cardiology.

Their conclusion is based on a review of 3 clinical trials (summarized below). It represents a huge setback for Multaq, which was at one time touted to be a potential blockbuster with annual sales in the billions.

Multaq “has only modest efficacy and no clear-cut safety advantage,” Kaul told the LA Times. The drug costs $9 per day, whereas amiodarone costs just a few cents. “Why would you want to use an expensive, ineffective alternative?”

Atrial fibrillation (AFib) affects 2.3 million Americans and causes about 71,000 deaths per year.

Afib is characterized by chaotic electrical and muscular activity in the upper chambers of the heart. The condition can predispose patients to strokes and can cause fatigue, dizziness, loss of consciousness or heart failure.

Amiodarone is highly effective in restoring normal cardiac rhythm in patients with Afib, but it is associated with frequent, potentially serious abnormalities of thyroid and lung function. Multaq was developed by Sanofi-Aventis as an alternative. 

The first trial showed that Multaq doubled the risk of death in patients with moderate- to high-risk for hospitalization and death from Afib.

The second showed that Multaq reduced hospitalizations from Afib, but there was no impact on mortality in lower risk patients.

The third revealed that Multaq was half as effective as amiodarone in preventing hospitalizations and deaths. There was no difference in the incidence of side-effects.

Soon after treatment onset, high-dose Lipitor cuts inflammation in carotid plaques and reduces the incidence potentially dangerous cerebral microemboli, say scientists from Cambridge University.

Their study also provides early validation of a new method for detecting inflammation in such plaques. This could prove to be a boon for those who study atherosclerosis of the carotid arteries, a risk factor for stroke.

Jonathan Gillard and colleagues test-drove ultrasmall superparamagnetic iron oxide particles as the contrast agent in their MRI-based study.

The particles are ingested by macrophages, a major constituent of inflamed plaques which often cause strokes.

Heretofore, the only noninvasive means to detect vessel inflammation had been fluorodeoxyglucose positron emission tomography, but radiation exposure associated with repeated PET scanning limits its use in studies requiring repeat scans to assess disease progress.

In the study, Gillard’s team randomized 47 high-risk plaque-afflicted patients to receive either 10- or 80-mg of Lipitor once per day for 12 weeks.

MRIs performed at 6 weeks revealed a marked reduction in macrophage activity, but only in the group randomized to receive 80 mg of Lipitor. MRIs at 12 weeks showed continued improvement, but again only in the high-dose group.

In these patients, cerebral microemboli counts, as measured by transcranial Doppler, fell 91% compared with baseline.

The write-up appears in the Journal of the American College of Cardiology.

“Our study may support the hypothesis that dampening of plaque inflammation rather than morphological regression (may be responsible for the) the early beneficial effects of statins seen in clinical practice,” wrote the scientists.

Still, it’s too early to pop the corks, at least for the new imaging technique. The contrast agent may promote oxidation of LDL cholesterol in the plaque which might cause it to destabilize and rupture.