New-onset atrial fibrillation (AF) is common in high-risk vascular patients, and the rate observed is considerably higher than that found in the general population, according to a post hoc analysis of the ONTARGET and TRANSCEND studies reported in a late-breaking clinical-trial session by Dr Paolo Verdecchia (Ospedale di Assisi, Italy) at the European Society of Hypertension (ESH) European Meeting on Hypertension 2011 here today.
In addition, despite the use of modern therapies, new-onset AF in these patients carries a high risk of severe complications, such as congestive heart failure and death, over a relatively short period of time, says Verdecchia.

The new analysis also identifies a previously unknown determinant of AF, hip circumference, he explained. Although the mechanism by which this may contribute remains unknown, he speculates that the hormone leptin—which is known to be a cardiostimulant and is found in hip tissue—may play a role.

All in all, the data indicate that the type of patients included in ONTARGET/TRANSCEND—those with prior MI, stroke, peripheral arterial disease, or complicated diabetes, who are at high vascular risk—are at great risk of developing AF “and should be treated aggressively,” Verdecchia told heartwire in an interview.

Asked to comment on the findings, AF expert Dr John Camm (St George’s Hospital, London, UK), said: “We know most of this information already from other sources, although it’s true that these are new data from these two trials, albeit with the caveat that it is a retrospective analysis.”

And Camm says a couple of the key results were interesting: first, the high rate of development of AF seen in this population, and second, the fact “that they were able to show, within a pretty short follow-up, a significant risk of adverse events and outcomes related to AF.” However, he says he was “surprised that they did not show that diabetes was associated with AF.”

AF is a growing epidemic; first look at incidence in high-risk patients

“AF is an epidemic, and although we have data on new-onset AF in hypertensive patients and the general population, the conclusions are not automatically applicable to higher-risk patients,” Verdecchia explained. “The determinants of AF and particularly the short-term outcomes are very poorly understood in this growing population of patients. This contemporary study examines this, for the first time.”

Using the ONTARGET/TRANSCEND megatrial database, which included patients with coronary artery disease, cerebrovascular disease, peripheral arterial disease, or complicated diabetes, Verdecchia and colleagues excluded those who had AF at baseline or those with missing information about AF or BP at baseline, to include a total of 30 424 patients.

In the trial, 12-lead ECGs were performed at randomization and at two years and five years of follow-up. Verdecchia and colleagues assessed the two-year ECGs and divided the patients into those with new-onset AF, approximately 1000 patients, and the remainder, who were classified as remaining in sinus rhythm. He noted, however, they were unable to distinguish between paroxysmal, sustained, and chronic AF.

The rate of new-onset AF was high over the 4.7 years of follow-up, 1.5 per 100 patients per year, and differed according to age, with a rate of 1% per year in those under 60 years of age and 2% per year in those over 60, figures that are “considerably higher than those seen in the general population,” Verdecchia commented.

New-onset AF was associated with several previously identified risk factors, including history of hypertension—which was associated with a 34% higher risk of new AF—age, ethnicity, creatinine levels, and left ventricular hypertrophy. Obesity was also a determinant of AF, but hip circumference, rather than waist, was the strongest anthropometric predictor of new-onset AF, a novel finding, he said. Diabetes, however, did not appear to be a predictor of AF in this population, a finding that is at odds with most other research in this field.

And alarmingly, “in a very short period of time, just a few years, new-onset AF was associated with a significantly higher risk of cardiovascular mortality and congestive heart failure,” said Verdecchia.

HRs of outcomes in patients with new-onset AF compared with those who remained in sinus rhythm

a. Adjusted for age, sex, hypertension, diabetes, CAD, systolic and diastolic BP, serum creatinine, and serum glucose
b. p<0.05
c. p<0.01

Unexpectedly, however, the risk of MI decreased in patients with new AF, perhaps because of the greater use of anticoagulants such as warfarin in these patients, he noted. There were 48.7% of those with new-onset AF taking vitamin-K antagonists, compared with just 5.2% of those patients who remained in sinus rhythm.

Source: theheart.org