Potpara TS, Polovina MM, Licina MM et al.
Eur J Heart Fail. 2013 Apr;15(4):415-24.

Background

Atrial fibrillation (AF) and heart failure (HF) often coexist and share risk factors. These conditions also been seem to influence the clinical severity of the other. AF may lead to HF in patients without a history of prior HF or structural heart disease [1-4]. Most studies evaluating the added prognostic significance of existing AF and HF for thromboembolic events (TE) considered patients with established HF [5-8]. Less is known about the risk factors for and prognostic implications of incident HF development in patients with first diagnosis of AF and structurally normal hearts.
As risk factors may accumulate in life, and structural and functional myocardial changes may develop over time, patients in later stages of AF likely have many common risk factors for HF development [9]. The risk profile of these patients in earlier stages of AF might however be different, in the absence of overt structural cardiac alterations.
Therefore, the current study investigated baseline risk factors for development of clinically manifested incident HF in patients with first-diagnosed non-valvular AF and structurally normal hearts. 842 patients were included and reached the pre-planned 5 year follow-up. A composite endpoint of progression to permanent AF, stroke/systemic TE, ischaemic stroke, cardiovascular death, or all-cause mortality was used.

Main results

• History of hypertension (HR=2.3, 95%CI: 1.5-3.8, P<0.001), history of diabetes (HR=2.0, 95%CI: 1.1-4.0, P=0.048), dilated left atrium (HR=1.8, 95%CI: 1.1-2.8, P=0.018) and low-normal LVEF (HR=2.6, 95%CI: 2.0-3.5, P<0.001) were independent predictors of subsequent HF.
• Patients with subsequent HF more frequently received drugs for rate control, oral anti-coagulants, ACE inhibitors or ARBs and diuretic and showed more adverse outcome events than patients who did not develop HF.
• Of 83 patients with subsequent HF, 60.2% were diagnosed with HF with preserved EF (PEF), whereas 39,8% developed HF with reduced EF (REF). HF with PEF or REF were both significantly associated with most of the outcome events.
• 3.1% of the total study population experienced reduced LVEF without clinically overt HF. Asymptomatic LVEF reduction was not identified as an independent risk factor for the composite endpoint, but it was significantly associated with the occurrence of stroke/TE

Conclusion

Even mild LA dilatation or low-normal LVEF in the absence of overt underlying heart disease at the start of this study turned out to increase risk for incident HF in subsequent years. Incident clinical HF was a predictor of adverse outcomes, as were HF with PEF or REF.
These relatively young patients with first diagnosed AF and structurally normal hearts might be considered individuals at low risk. Subtle alterations of myocardial function such as mild LA dilatation could become clinically overt over a longer period. Further studies may advise whether careful monitoring and intervention directed at modifying CV risk factors can improve long-term outcome.

Editorial comment [10]

In patients who have developed AF, prediction of AF-related complications is of great clinical importance. The authors describe certain conditions that are predictors of later HF.
The fact that only patients with structurally normal hearts and LVEF > 50% were included raises questions on the generalizability of the results to other AF cohorts. Also, this risk score can only be used after echocardiography has been performed.
Nevertheless, this study helps classify AF patients at high or very low-risk of developing HF. This is not only important for risk communication and motivation of the patients, but can also help choose treatment strategy and avoid potential harmful therapies in low-risk patients. Other studies should provide us with insights whether we can reverse the modelling process at an early stage.

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