FREEDOM Substudy: CABG, PCI Outcomes Affected by Baseline BP


LONDON, England—Baseline systolic blood pressure (BP) not only affects long-term outcomes after revascularization but, when slightly elevated, means that patients are more likely to benefit from CABG compared with PCI, according to a subanalysis of the FREEDOM trial presented on August 30, 2015, at the European Society of Cardiology Congress.


The Take Home


Patients should aim to meet guideline BP targets at 1 year after revascularization, study author suggests.


The latter finding suggests that “current recommendations to drive systolic [BP] below 140 mmHg in diabetic patients with multivessel CAD should be tailored according to the mode of coronary revascularization,” says presenter Michael E. Farkouh, MD, MSc, of Mount Sinai Hospital (New York, NY).

The FREEDOM trial randomized 1,900 patients with diabetes and CAD to either PCI with DES or CABG at 140 international centers. CABG was found to be associated with better long-term outcomes than PCI in this population, a difference driven by lower rates of MI and stroke at 5 years.  

For the substudy, Dr. Farkouh and colleagues classified 1,852 patients (mean age 63 years; 71.6% men) by their baseline systolic BP into 3 groups:

  • < 140 mm Hg (n = 1,150)
  • 140-160 mm Hg (n = 541)
  • > 160 mm Hg (n = 161)

Patients with BP < 140 mm Hg tended to be younger and were more likely to be male, to smoke, and have a history of MI than those with higher values. About one-quarter were diagnosed with previous heart failure.  

Among PCI patients, there were no differences in 5-year MACCE (all-cause mortality, nonfatal MI, or nonfatal stroke) based on baseline systolic BP (overall log-rank P = .23). This similarity remained after adjustment for age, sex, history of MI and/or heart failure, and active smoking.  

However, increased event rates were seen in CABG-treated patients who had baseline systolic BPs of > 160 mmHg (HR 2.09) and < 130 mmHg (HR 1.33), while those in the 140-160 mmHg range reported the lowest risk of events (HR 0.88).

On Kaplan-Meier analysis, patients with slightly elevated baseline systolic BP were more likely after PCI than after CABG to experience MACCE (28.4% vs 14.6%; P = .002) or die (16.2% vs 8.6%; P = .04) within 5 years.

The greatest disparity between CABG and PCI was seen in those with slightly elevated systolic BP (table 1). 

Table 1. Risk of Outcomes at 5 Years: PCI vs CABG

Table 1.  Risk of Outcomes at 5 Years: PCI vs CABG

a
P for interaction = .08 
b P for interaction = .32.

Session co-moderator Stephan Achenbach, MD, of the University of Erlangen (Erlangen, Germany), said it is “interesting to see that the group with higher BP values also contained more female patients and they were older.”

Although researchers adjusted for those factors, Dr. Farkhou said, the observational data still has its limits. 

Additionally, he observed that patients who started with high BP at the beginning of the study tended to end up with high BP. “Of course we don’t want to send a message that everyone should have uncontrolled BP, but what we’re trying to say is that at the time of bypass—that very important time in that first 30 days when strokes and graft occlusion occur—this may be a mechanism to explain the findings of trial. We don’t think people are changing their category, and that’s something that we had hypothesized early on,” Dr. Farkouh said.

His team is now evaluating target systolic BP optimization in CABG patients as well as coronary perfusion pressure and other explanations for these findings, Dr. Farkouh reported. “We believe this warrants prospective evaluation,” he concluded, adding that “our message is we’d like to have patients assume guideline targets after the first 6 months to 1 year. We just don't have the evidence for that.”



Source:

Farkouh M. The influence of baseline systolic blood pressure on major cardiovascular and cerebrovascular outcomes in the FREEDOM Trial: FREEDOM BP. Presented at: European Society of Cardiology Congress; August 30, 2015; London, England.

Disclosures:

  • FREEDOM was funded through a grant from the National Heart, Lung, and Blood Institute and supported by Boston Scientific, Cordis, Eli Lilli, and Sanofi.
  • Dr. Farkouh reports no relevant conflicts of interest.

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