Resistant hypertension (RH) is an easily identifiable risk factor that has a notable prevalence among phase II cardiac rehabilitation participants and is associated with reduced exercise capacity and worse long-term outcomes among those participants.
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So suggest two companion studies from a large cohort presented Sept. 7 at the American Heart Association’s Hypertension 2019 Scientific Sessions by Luke Laffin, MD, a cardiologist in Cleveland Clinic’s Section of Preventive Cardiology and Rehabilitation.
“Cardiac rehab patients with resistant hypertension represent a high-risk group,” says Dr. Laffin. “They have worse outcomes at two years in terms of rehospitalizations, and their exercise capacity — even after completing cardiac rehabilitation — is lower than that of other participants.”
Dr. Laffin’s interest in these patients was spurred by the fact that prevalence of RH is unknown in certain clinical circumstances, including cardiac rehabilitation. “We know that the most recent blood pressure [BP] guidelines from the American College of Cardiology and American Heart Association strongly emphasize tighter BP control in patients with pre-existing cardiovascular disease or a high risk for cardiovascular disease,” he says. “Clearly, phase II cardiac rehabilitation patients fit that bill.”
Study 1: Prevalence and characteristics in cardiac rehab patients
Both studies presented by Dr. Laffin drew on a cohort of 504 patients who participated in phase II cardiac rehab at Cleveland Clinic from 2012 to 2017. At initial intake into rehab, all participants were evaluated for RH, defined as follows:
- Resting systolic BP ˃ 130 mmHg despite use of three antihypertensive medications, including a diuretic
- Use of four or more antihypertensive medications regardless of blood pressure
The first study focused on the prevalence of RH in this sample and its accompanying patient characteristics. “We had done a literature review and found no other studies examining the prevalence of resistant hypertension in a population like this,” Dr. Laffin explains.
He and colleagues found that 63% of the 504 cardiac rehab participants carried a diagnosis of hypertension. Eleven percent of those patients — or 7% of the overall sample — were classified as having RH.
Analysis showed that patients with RH were significantly older than their non-RH counterparts, had higher systolic blood pressure and higher pulse pressure, and were more likely to be African-American. Patients with RH also demonstrated significantly higher rates of comorbid type 2 diabetes mellitus, peripheral artery disease and heart failure with reduced ejection fraction.
Study 2: Exercise capacity and outcomes
A companion study sought to ascertain whether cardiac rehabilitation affects exercise capacity and outcomes in patients with RH.
Of the 504 patients from the above cohort, 298 completed stress testing at both entry to and exit from cardiac rehab. Within this subpopulation with pre/post stress testing, 8% had RH, 62% had nonresistant hypertension and 30% had normal blood pressure.
Compared with other cardiac rehab participants, those with RH exhibited the following:
- Lower absolute baseline exercise capacity (5.4 ± 2.4 METs vs. 6.9 ± 2.6 METs; P = 0.007)
- Lower exercise capacity after completion of cardiac rehab (6.6 ± 2.6 METs vs. 8.4 ± 3.0 METs; P = 0.004)
- A similar relative increase in exercise capacity from the start to the completion of cardiac rehab (31% vs. 28%; P = 0.74)
Moreover, among all 504 participants, those with RH were more likely to be hospitalized within two years of completing cardiac rehab (67% vs. 39%; P = 0.002) and showed a trend toward increased mortality within five years (8% vs. 4%; P = 0.18).
Takeaways for clinicians
Dr. Laffin says that better understanding of the prevalence of RH in cardiac rehab patients should prompt clinicians involved in cardiac rehab programs to look for and treat the condition.
“Resistant hypertension is something we can easily identify because we check blood pressure in cardiac rehabilitation patients at every session — usually three times a week for three months,” he says. “The next steps are to move forward with that information so that patients with resistant hypertension are connected with hypertension specialists who can help them receive optimal guideline-directed care.”
He and his colleagues also want physicians to recognize the importance of cardiac rehab, which they note is much more than just supervised exercise. “Phase II cardiac rehabilitation is a wonderful program that’s been shown to reduce major adverse cardiac events,” says Leslie Cho, MD, Section Head of Preventive Cardiology and Rehabilitation at Cleveland Clinic. “It saves lives by helping patients control risk factors, teaching them healthy lifestyles and, most importantly, identifying high-risk patients for intervention.”
The above companion studies serve as a good starting point for looking at interventions to improve outcomes in individuals with RH, notes Dr. Laffin. He is now planning a prospective study to identify other hypertension subtypes, such as masked hypertension, in cardiac rehabilitation participants.