Phenomapping analysis identifies groups of heart failure patients

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 - Heart Failure - Don't use until 3/1/12

A phenomapping analysis of patients hospitalized for heart failure found that heart failure with preserved ejection fraction is a heterogeneous disorder and contains mutually exclusive groups with similar characteristics.

Lead researcher Sanjiv J. Shah, MD, of Northwestern University in Evanston, Ill., and colleagues wrote that this was the first study to examine phenomapping of a clinical cardiovascular syndrome. They also mentioned that the study was the first to demonstrate the feasibility and utility of phenomapping for the unbiased categorization of a cardiovascular disorder. Results were published in the Jan. 20 issue of Circulation.

The systematic observational study enrolled 420 patients enrolled at Northwestern University’s outpatient clinic between March 2008 and May 2011. Of the original cohort, 23 patients had incomplete phenotypic data and were excluded from the trial.

Patients in the study had heart failure and left ventricular ejection fraction of less than 50 percent and evidence of significant diastolic dysfunction, elevated left ventricular filling pressures or B-type natriuretic peptide (BNP) blood test reading more than 100 pg/mL . The mean age was 65, while 62 percent of patients were female and 39 percent were black.

After enrollment, patients were evaluated at least once every six months. At each visit, researchers documented patients’ intercurrent hospitalizations and documented them as resulting from cardiovascular or noncardiovascular causes.

Researchers performed phenotyping of the patients and evaluated them using statistical learning algorithms to define the groups. They also created a phenotype heat map, which showed substantial heterogeneity among patients. Through the heat map, researchers could group patients by certain characteristics, including increased heart pressure, right ventricular wall thickness, cardiac chamber enlargement and elevated body size.

The patients were categorized into three groups. The first group was younger and had lower BNP readings than the other groups. The second group had more patients with obesity, diabetes and obstructive sleep apnea. The third group had the oldest patients and included patients who were most likely to have chronic kidney disease and high BNP readings.

To validate the results, researchers prospectively enrolled an additional 107 patients in the program. However, they said that the lack of an external cohort was a potential study limitation. They also mentioned future studies are needed to demonstrate the generalizability of the results.