2016 Top Stories in Cardiology: Heart Failure
One of the more interesting studies in heart failure (HF) for the year 2016 was a provocative report by Tsao and colleagues.1 These authors examined the clinical outcomes and prognoses of patients with a “borderline” left ventricular ejection fraction (LVEF) of 50% to 55% in a large community-based cohort (Framingham Heart Study). Tsao et al found that an LVEF of 50% to 55% was associated with an approximate 35% increase in the risk of HF or death, and a more than twofold increased risk in the development of incident HF. The development of HF could not be explained by an intercurrent myocardial infarction, which occurred in only 8% of the patient population.
Given that we currently define HF with a reduced ejection (HFrEF) as an LVEF ≤40% and HF with a preserved ejection (HFpEF) as an LVEF ≥50%, the study by Tsao and colleagues raises the provocative question of whether LVEF can or should be used to identify HF patients. However, before we “throw out” LVEF as a reliable diagnostic tool, there are two aspects of the Tsao study that are worth highlighting. The first is that patients with a borderline LVEF of 50% to 55% had a higher prevalence of cardiovascular disease, as well as a history of a prior myocardial infarction, compared with those with more normal LVEFs. Accordingly, many of the patients with a borderline LVEF would be categorized as having “stage A” HF (ie, no structural heart disease but at risk for developing HF). Thus, many of these patients had a higher likelihood of developing HF, regardless of their baseline LVEF. Second, these patients were followed for 8 years, during which time it is possible that subclinical cardiac injury, although not obvious on a 2D echocardiogram, could have resulted in progressive cardiac remodeling with the subsequent development of HFrEF. Alternatively, some of the patients with an LVEF between 50% and 55% could have had asymptomatic HFpEF and subsequently developed worsening diastolic dysfunction over the 8 years of follow-up. Although serial 2D imaging studies were not obtained in the majority of the patients, it is noteworthy that 63% of the patients in the Tsao study developed HFrEF, whereas 33% of the patients developed HFpEF.
There are two reasons why I chose the study by Tsao and colleagues as one of the most important studies of the year. The first is that this study highlights the need to develop a new taxonomy for classifying HF patients that defines HF by its molecular causes, in addition to traditional physical signs and symptoms and assessment of LVEF. The second, and perhaps more important reason, is that the study by Tsao et al emphasizes the need for more aggressive treatment of comorbidities in stage A patients who are at high risk for developing HF. The most effective way to treat HF is to prevent it from happening in the first place.
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