Conference Coverage

Cardiac biomarkers refine antihypertensive drug initiation decisions


 

REPORTING FROM AHA 2019

– Incorporation of cardiac biomarkers into current guideline-based decision-making regarding initiation of antihypertensive medication in patients with previously untreated mild or moderate high blood pressure leads to more appropriate and selective matching of intensive blood pressure control with true patient risk, Ambarish Pandey, MD, reported at the American Heart Association scientific sessions.

Dr. Ambarish Pandey, cardiologist at the University of Texas Southwestern Medical Center, Dallas. Bruce Jancin/MDedge News

Dr. Ambarish Pandey

That’s because the 2017 American College of Cardiology/AHA blood pressure guidelines recommend incorporating the ACC/AHA 10-Year Atherosclerotic Cardiovascular Disease (ASCVD) Risk Calculator into decision making as to whether to start antihypertensive drug therapy in patients with stage 1 hypertension (130-139/80-89 mm Hg), but the risk calculator doesn’t account for the risk of heart failure.

Yet by far the greatest benefit of intensive BP lowering is in reducing the risk of developing heart failure, as demonstrated in the landmark SPRINT trial, which showed that intensive BP lowering achieved much greater risk reduction in new-onset heart failure than in atherosclerotic cardiovascular events.

Thus, there’s a need for better strategies to guide antihypertensive therapy. And therein lies the rationale for incorporating into the risk assessment an individual’s values for N-terminal pro–brain natriuretic peptide (NT-proBNP), which reflects chronic myocardial stress, and high-sensitivity cardiac troponin T (hs-cTnT), which when elevated signals myocardial injury.

“Cardiac biomarkers are intermediate phenotypes from hypertension to future cardiovascular events. They can identify individuals at increased risk for atherosclerotic events, and at even higher risk for heart failure events,” explained Dr. Pandey, a cardiologist at the University of Texas Southwestern Medical Center, Dallas.

He presented a study of 12,987 participants in three major U.S. cohort studies: the Atherosclerosis Risk In Communities (ARIC) study, the Multi-Ethnic Study of Atherosclerosis (MESA), and the Dallas Heart Study. At baseline, none of the participants were on antihypertensive therapy or had known cardiovascular disease. During 10 years of prospective follow-up, 825 of them experienced a first cardiovascular disease event: 251 developed heart failure and 574 had an MI, stroke, or cardiovascular death. Dr. Pandey and his coworkers calculated the cardiovascular event incidence rate and number-needed-to-treat with intensive antihypertensive drug therapy to prevent a first cardiovascular disease event on the basis of whether patients in the various BP categories were positive or negative for one or more biomarkers.

The results

Fifty-four percent of subjects had normal BP, defined in the guidelines as less than 120/80 mm Hg. Another 3% had BP in excess of 160/100 mm Hg. No controversy exists regarding pharmacotherapy in either of these groups: It’s not warranted in the former, essential in the latter.

Another 3,000 individuals had what the ACC/AHA guidelines define as elevated BP, meaning 120-129/<80 mm Hg, or low-risk stage 1 hypertension of 130-139/80-89 mm Hg and a 10-year ASCVD risk score of less than 10%. Initiation of antihypertensive medication in these groups is not recommended in the guidelines. Yet 36% of these individuals had at least one positive cardiac biomarker. And here’s the eye-opening finding: Notably, the 10-year cardiovascular event incidence rate in this biomarker group not currently recommended for antihypertensive pharmacotherapy was 11%, more than double the 4.6% rate in the biomarker-negative group, which in turn was comparable to the 3.8% in the normal BP participants.

Antihypertensive therapy was recommended according to the guidelines in 20% of the total study population, comprising patients with stage 1 hypertension who had an ASCVD risk score of 10% or more as well as those with stage 2 hypertension, defined as BP greater than 140/90 mm Hg but less than 160/100 mm Hg. Forty-eight percent of these subjects were positive for at least one biomarker. Their cardiovascular incidence rate was 15.1%, compared to the 7.9% rate in biomarker-negative individuals.

The estimated number-needed-to-treat (NNT) with intensive blood pressure–lowering therapy to a target systolic BP of less than 120 mm Hg, as in SPRINT, to prevent one cardiovascular event in individuals not currently guideline-recommended for antihypertensive medications was 86 in those who were biomarker-negative. The NNT dropped to 36 in the biomarker-positive subgroup, a far more attractive figure that suggests a reasonable likelihood of benefit from intensive blood pressure control, in Dr. Pandey’s view.

Similarly, among individuals currently recommended for pharmacotherapy initiation, the NNTs were 49 if biomarker-negative, improving to 26 in those positive for one or both biomarkers, which was comparable to the NNT of 22 in the group with blood pressures greater than 160/100 mm Hg. The NNT of 49 in the biomarker-negative subgroup is in a borderline gray zone warranting individualized shared decision-making regarding pharmacotherapy, Dr. Pandey said.

In this study, an elevated hs-cTnT was defined as 6 ng/L or more, while an elevated NT-proBNP was considered to be at least 100 pg/mL.

“It’s noteworthy that the degree of elevation in hs-cTnT and NT-proBNP which were observed in our study were pretty subtle and much below the threshold used for diagnosis of ischemic events or heart failure. Thus, these elevations were largely representative of subtle chronic injury and not acute events,” according to the cardiologist.

One audience member asked if the elevated biomarkers could simply be a surrogate for longer duration of exposure of the heart to high BP. Sure, Dr. Pandey replied, pointing to the 6-year greater average age of the biomarker-positive participants.

“It is likely that biomarker-positive status is capturing the culmination of longstanding exposure. But the thing about hypertension is there are no symptoms that can signal to the patient or the doctor that they have this disease, so testing for the biomarkers can actually capture the high-risk group that may have had hypertension for a long duration but now needs to be treated in order to prevent the advance of downstream adverse events,” he said.

Dr. Pandey reported having no financial conflicts of interest regarding his study, conducted free of commercial support.

SOURCE: Pandey A. AHA 2019 Abstract EP.AOS.521.141

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