Preserved-EF HF Portends Worse CABG Survival: SWEDEHEART

STOCKHOLM, SWEDEN — Heart failure (HF) with preserved ejection fraction (pEF) was significantly and independently associated with worse survival after CABG in a nationwide population-based study from Sweden^[1].

"Traditionally, risk assessment before CABG has focused on left ventricular ejection fraction, so in a sense, it was somewhat surprising that a history of HF so strongly contributed to risk," senior author Dr Ulrik Sartipy (Karolinska University Hospital, Stockholm, Sweden) told heartwire from Medscape by email.

The study, published online July 13, 2016 in JAMA Cardiology, was based on all 41,906 patients in the SWEDEHEART registry who underwent primary isolated CABG between January 2001 and December 2013. Reduced EF (rEF) was defined as less than 50% and pEF as 50% or higher.

All-cause mortality 30 days after surgery was 0.8% in patients with no HF and pEF (n=27,165), and 2.9%, 2.8%, and 4% in those with no HF and rEF (n=10,069), HFpEF (n=1216), and HFrEF (n=3456).

After adjustment for 20 different risk factors, including diabetes, prior MI or PCI, atrial fibrillation, and emergent surgery, the hazard ratios for early death were 1 (no HF and pEF) vs 2.25 (95% CI 1.86–2.73) (no HF and rEF), 1.83 (95% CI 1.26–2.66) (HFpEF), and 2.52 (95% CI 1.99–3.19) (HFrEF).

"A major implication of our study is that referring cardiologists and cardiac surgeons should be aware that a history of HF is an additional, independent, and important risk factor for early death that the currently used risk models do not take into consideration," write the investigators, led by Dr Magnus Dalén (Karolinska University Hospital).

This includes the popular EuroSCORE II and Society of Thoracic Surgeons cardiac surgery risk models, which take into account left ventricular EF and NYHA functional classification but do include not HF history. The investigators note that NYHA function is a classification of the grade of limitation during physical activity and cannot be considered equal to a previous HF diagnosis.

With longer follow-up, a history of HF was also shown to be an important and independent risk factor for long-term outcomes after CABG regardless of preoperative EF.

After a mean of 6 years follow-up, 13.2% of the reference group died, compared with 24.6%, 33.9%, and 42.9% with no HF and rEF, HFpEF, and HFrEF.

Compared with the reference group, the adjusted hazard ratios for all-cause mortality were 1.47 (95% CI 1.40–1.56), 1.62 (95% CI 1.46–1.80), and 2.29 (95% CI 2.14–2.44), respectively.

"The heart-failure syndrome is a strong predictor of long-term outcomes following CABG. Therefore, it is vital that patients with heart failure are followed carefully post-CABG by heart-failure cardiologists, even if they have normal or preserved ejection fraction," Sartipy said.

HFrEF is well known to be associated with higher operative risk and worse long-term prognosis following CABG, but the risk and prognosis in patients with HFpEF undergoing CABG has been investigated only in a few and small studies previously, he said, observing that this is the largest study to date to investigate prognosis in this setting.

As noted in the article, a limitation of the study is that clear diagnostic criteria for HFpEF are lacking, which leads to difficulties regarding direct comparisons between studies. Further, studies suggesting similar mortality have generally been unadjusted epidemiological surveys, he said.

Other limitations are a lack of information on NYHA class, medical treatment, whether revascularization was considered complete, and time between EF assessment and CABG.

Going forward, the value and mode of revascularization (PCI or CABG) in HFpEF need to be assessed to inform patients and doctors regarding optimal treatment in HFpEF and CAD and to establish optimal medical therapy to improve their post-CABG prognosis, Sartipy said.

The study was supported by grants from the Swedish Society of Medicine, Karolinska Institute Foundations and Funds, Mats Kleberg Foundation, Swedish Research Council, and Swedish Heart-Lung Foundation. The authors report no relevant financial relationships.

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