Risk of nonstroke events underappreciated in atrial fibrillation

OXFORD, UK — A meta-analysis finds that patients with atrial fibrillation (AF) are at higher risk for a range of cardiovascular and renal events—with the risk for heart failure far outstripping that for the long-recognized complication of stroke[1].

After examining 104 cohort studies involving 9.68 million participants, UK researchers found that AF was associated with a 64% higher risk of chronic kidney disease, 88% higher risk of sudden cardiac death, and 96% higher risk of a major CV event.

Among patients with AF vs those without, the risk was fivefold higher for congestive heart failure compared with a 2.3-fold risk for stroke, according to data published online September 6, 2016 in the BMJ.

Principal investigator Dr Ayodele Odutayo (University of Oxford, UK) told  heartwire from Medscape that the study is unable to prove causality based on the data, "but when you see associations across a range of diseases it suggests atrial fibrillation is acting as a marker for shared underlying risk factors for cardiovascular disease."

He noted, for instance, that hypertension is diagnosed in up to 90% of patients with AF but also contributes to chronic kidney disease, the development of heart failure, and MI.

Odutayo also pointed out that non–vitamin K antagonist oral anticoagulants (NOACs) have been the focus of clinical care in AF and have shown to be equivalent to warfarin with respect to stroke outcomes, "but they don't provide any added benefit for nonstroke outcomes. So again, it raises the question of whether atrial fibrillation is causing these cardiovascular outcomes or whether it's just an association."

The analysis included 587,867 participants with AF. The associations between AF and nonstroke outcomes were broadly consistent across subgroups and in sensitivity analyses.

Atrial fibrillation and nonstroke outcomes

Outcome

Relative risk

95% CI

Heart failure

4.99

3.04–8.22

Stroke

2.42

2.17–2.71

CV mortality

2.03

1.79–2.30

Major CV events

1.96

1.53–2.51

Sudden cardiac death

1.88

1.36–2.60

Chronic kidney disease

1.64

1.41–1.91

Ischemic heart disease

1.61

1.38–1.87

All-cause mortality

1.46

1.39–1.53

Peripheral arterial disease

1.31

1.19–1.45


CKD risk

Odutayo said the findings for heart failure are quite clear and consistent with other studies. They were cautious, however, about overstating the findings for renal disease, particularly as the risk was lower than that for stroke and data for this outcome were pooled from only three studies.

Still, he noted that the finding is interesting and pointed out that renal disease patients are often excluded from CV trials even though CVD is one of the leading causes of mortality in this population.

"Certainly the finding is there," and "we think it would be important to consider renal disease as an outcome in future trials," Odutayo added.

Primary-prevention push

The investigators write that the overall findings "could have implications for prioritization of public-health resources" and that AF patients would benefit from the development of novel interventions as well as "a focus on primary prevention and management of cardiovascular risk factors."

Odutayo acknowledged that pushing primary prevention can be challenging for clinicians "because sometimes it sounds like we're giving the same message over and over" but noted that emerging evidence from trials like SPRINT shows that clinicians can do even better, for example, with hypertension control.

"It's important that in upcoming guidelines these ideas are echoed and strongly endorsed and then as practitioners we have to figure out ways to increase the uptake of these new ideas about how to manage hypertension and these risk factors. And it will benefit not only the AF patients but also people without AF."

Odutayo reported support from the Rhodes Trust. Disclosures for the coauthors are listed in the article.

References
  1. Odutayo A, Wong CX, Hsaio AJ, et al. Atrial fibrillation and risks of cardiovascular disease, renal disease, and death: systematic review and meta-analysis. BMJ 2016; DOI:10.1136/bmj.i4482. Article

Source: Medscape