Long-Term Stroke and Mortality Risk in Patients with Secondary Atrial Fibrillation

Analysis of a large patient cohort indicates that “isolated” events of atrial fibrillation precipitated by temporary secondary conditions tend to become chronic long-term cases of atrial fibrillation.

“Guidelines have proposed that atrial fibrillation can occur as an isolated event, particularly when precipitated by a secondary, or reversible, condition,” the study authors wrote in Circulation.

“However, atrial fibrillation (AF) recurs in most individuals, including those diagnosed with secondary precipitants. Long-term AF-related stroke and mortality risks were similar between individuals with and without secondary AF precipitants,” they said.

The study team pulled records from the Framingham Heart Study on 1,409 patients with newly diagnosed atrial fibrillation and compared outcomes of patients whose atrial fibrillation appeared to stem from a secondary precipitant with those whose atrial fibrillation appeared to stem from a permanent condition.

Standard guidelines were used to define secondary precipitants: surgery, infection, acute myocardial infarction, thyrotoxicosis, acute alcohol consumption, acute pericardial disease, pulmonary embolism, or other acute pulmonary disease.

Overall, there were 439 patients diagnosed with atrial fibrillation while they were undergoing a secondary precipitant, a figure equal to 31% of the total patient cohort. The most common of those precipitants were cardiothoracic surgery (n=131, 30%), infection (n=102, 23%), non-cardiothoracic surgery (n=87, 20%), and acute myocardial infarction (n=78, 18%).

Atrial fibrillation recurred in 544 of the 846 patients who were initially diagnosed with paroxysmal arrhythmias, but it was significantly less likely to recur in those patients whose atrial fibrillation was first diagnosed when they were experiencing secondary precipitants. Indeed, the 5-year, 10-year and 15-year recurrence rates for such patients were 42%, 56% and 62%, compared to 59%, 69% and 71% in patients with no secondary precipitants (multivariable-adjusted hazard ratio [HR] 0.65; 95% confidence interval [CI], 0.54 to 0.78).

Patients whose initial atrial fibrillation was diagnosed amidst precipitating factors also suffered significantly (though only just significantly) less heart failure than other patients (HR 0.74; 95% CI 0.56 to 0.97).

There was, however, no significant difference in the stroke risk between the 2 populations (HR 1.13; 95%CI 0.82 to 1.57) and mortality rates were identical (HR 1.00; 95%CI 0.87 to 1.15).

The study authors believe the prospective nature of the patient cohort that supplied their records, along with the extremely long follow-up period, provided them with a particularly powerful data set for their investigation and lent particular weight to the conclusion that, for the most part, people whose atrial fibrillation stems from secondary precipitants don’t fare much better than those whose atrial fibrillation stems from more permanent causes.

That said, the authors of the new study think there is hope that proper treatment could make more cases of atrial fibrillation as temporary as the secondary precipitants that cause them and, therefore, improve outcomes for a significant percentage of all the people who develop atrial fibrillation.

Some studies have already concluded that certain strategies allow physicians to significantly reduce the number of cases that arise from certain secondary precipitants. Continuing certain medications immediately before and after surgery, for example, has been shown to help some patients avoid arrhythmias, but more research has yet to demonstrate whether such atrial fibrillation can be permanently vanquished once it arises.

“Future studies,” the authors of the new paper wrote, “may determine whether increased arrhythmia surveillance or adherence to general atrial fibrillation management principles in patients with reversible atrial fibrillation precipitants will reduce morbidity.”