Cardioversion of atrial fibrillation with ibutilide: When is it most effective?

BACKGROUND: Atrial fibrillation (AF) is found in 1% of persons above the age of 60 years. More than 5% of the population older than 69 years and about 14% of octogenarians are at risk for this arrhythmia. It is estimated that 1.5 to 3 million persons in the United States alone suffer from AF. The public health implications and attendant morbidity are a significant drain on our health care system. HYPOTHESIS: The purpose of this study was to determine the clinical and echocardiographic predictors of success in converting AF of > or = 24 h duration. METHODS: Demographic and clinical and echocardiographic parameters of 101 patients with recent onset AF (> 24 h) who received ibutilide were studied. RESULTS: Of 101 patients, 56 (55%) converted to sinus rhythm. Age, gender, hypertension, diabetes mellitus, left ventricular ejection fraction (< or = 35%), congestive heart failure, and previous medication for rate control had no significant effect on the conversion rate. Conversion rate was only 30% (9/30 patients) in the presence of an enlarged left atrium (LA > or = 5 cm) and 37.7% (23/61 patients) in the presence of mitral valve disease (MVD), whereas the conversion rate was 82.5% (33/40 patients) in the absence of MVD and 85% (29/34 patients) in the absence of both enlarged LA and MVD (p = <0.001). Patients with coronary artery disease (CAD) also exhibited a significantly greater response to ibutilide than patients without CAD (77 vs. 46%, p-value 0.005). CONCLUSION: As a therapy for cardioversion of AF, ibutilide is most effective in a selected subgroup patients, such as in patients with CAD and in patients without MVD and/or markedly enlarged left atrium.     

Mortality in atrial fibrillation. Is it changing?

Patients with atrial fibrillation experience higher mortality rates than those without this condition. Recent studies have explored whether mortality rates in atrial fibrillation patients and the overall impact of atrial fibrillation on mortality has changed. Overall, mortality in atrial fibrillation has decreased over the last few decades, with no strong differences between men and women. These improvements could be caused by advances in preventing thromboembolic complications of atrial fibrillation or better management of comorbidities in these patients. Understanding the mechanisms for these changes and developing novel approaches to improve survival in AF patients are areas deserving of future research.     

Colorectal cancer and risk of atrial fibrillation and flutter: a population-based case–control study

Colorectal cancer has recently been associated with an increased atrial fibrillation risk, but evidence is very sparse. So, we conducted a population-based case-control study in northern Denmark (population 1.7 million) during 1998-2006 to estimate the atrial fibrillation/flutter risk in colorectal cancer patients. We identified 28,333 atrial fibrillation/flutter cases and 283,260 sex-, age-, and county-matched population controls. We searched the databases for a prior colorectal cancer diagnosis, a prior cancer diagnosis other than colorectal cancer, and performance of surgery within 30 days prior to atrial fibrillation/flutter. We used conditional logistic regression to estimate the OR of atrial fibrillation/flutter in patients with colorectal cancer, cancers other than colorectal and in patient with surgery. Among cases, 0.59% (n = 168) had a colorectal cancer diagnosis within 90 days before their atrial fibrillation/flutter diagnosis, compared with 0.05% (n = 155) of controls (adjusted OR = 11.8; 95% CI 9.3-14.9). Beyond the first 90 days after a colorectal cancer diagnosis, atrial fibrillation/flutter risk was no longer increased. There was likewise an increased atrial fibrillation/flutter risk in patients diagnosed with another cancer form in the prior 90 days (OR = 7.0, 95% CI 6.3-7.8). Furthermore, the atrial fibrillation/flutter risk was elevated fivefold in patients who had undergone surgery, whether or not cancer-related. We therefore conclude that colorectal cancer patients are at increased atrial fibrillation/flutter risk exclusively in the first 90 days after cancer diagnosis, but to no greater an extent than are patients with other cancers. The performance of surgery probably plays an important role in this association.     

Therapeutic implications of atrial fibrillation mechanisms: can mechanistic insights be used to improve AF management?

Atrial fibrillation (AF) is a very common clinical problem, and presently available treatment options are suboptimal. A tremendous amount has been learned over the past 10 years about the atrial substrates that support sustained AF at the tissue, ionic and molecular levels. This understanding of the fundamental mechanisms underlying AF has opened up a variety of new, rationally-based therapeutic approaches. The present paper reviews what is known about the mechanistic substrates that lead to AF and discusses the potential therapeutic consequences.