Hypertension, Underuse of Beta-Blockers Linked to Recurrent Tear in SCAD Patients

New research implicates underlying hypertension and lack of beta-blocker therapy as contributors to the high rate of recurrence of spontaneous coronary artery dissection (SCAD) following initial treatment.

Studies have suggested that up to 30% of SCAD patients, who historically have tended to be young women, experience a recurrence over long-term follow-up. Lack of data on these patients has been an ongoing issue since the condition is relatively infrequent, accounting for an estimated 1.7% to 4% of all ACS cases and about 0.5% of all sudden cardiac deaths, say researchers led by Jacqueline Saw, MD (University of British Columbia, Vancouver, Canada).

In a paper in the August 29, 2017, issue of the Journal of the American College of Cardiology, Saw and colleagues say the lack of randomized trials to guide therapy, combined with uncertainty over optimal treatment strategies to minimize recurrence, highlights the importance of understanding and addressing critical risk factors.

Among the 327 troponin-positive ACS patients with nonatherosclerotic SCAD treated at the study authors’ institution between 2012 and 2016, those with hypertension were more than twice as likely to have a recurrence over 3 years of follow-up (HR 2.46; 95% CI 1.23–4.93), while beta-blocker use was associated with greatly reduced risk of recurrent SCAD (HR 0.36; 95% CI 0.18–0.73).

“It was surprising that some of the other potential predisposing factors such as [fibromuscular dysplasia] . . . and other cardiovascular risk factors that we looked at did not pan out,” Saw told TCTMD.

She added that said the explanation may lie in arterial shear stress, which is increased in patients with hypertension and can be decreased with beta-blocker use.

In an accompanying editorial, Marysia S. Tweet, MD (Mayo Clinic College of Medicine, Rochester, MN), and Jeffrey W. Olin, DO (Icahn School of Medicine at Mount Sinai, New York, NY), agree with this assessment, but note that “much remains to be understood regarding the complex intracoronary hemodynamics, effects of shear stress, and subsequent remodeling.”

Support for Beta-Blockade

In the study cohort, which was 90.5% female, initial presentation was non-STEMI in 74.3%. Nearly half of all patients reported precipitating emotional stressors, with about one-quarter reporting physical stressors. Over 60% of patients had fibromuscular dysplasia, 11.9% had systemic inflammatory disease, and about 30% had more than one cardiovascular risk factor. Patients frequently reported migraines, depression, or anxiety. A single coronary artery was affected in most cases. Initial treatment was medical therapy in 83.1%, with only 16.5% undergoing PCI and 2.2% treated with CABG.

MACE occurred at a rate of 19.9% over the follow-up period, and was primarily in the form of MI. Recurrent SCAD was seen in 10.4%.

“Current guidance on how to treat SCAD patients is based largely on expert opinion, and a lot of clinicians do suggest that patients be on beta-blockers long term, primarily because they have suffered an MI and that’s a routine recommendation anyway,” Saw said. She added that data from aortic dissection patients lend additional support for the potential benefit of beta-blocker therapy in SCAD by suggesting that the agents can reduce the risk of rupture and aneurysm formation.

“Beta-blockers have been strongly recommended in many review papers, but there are no randomized data to support that,” she told TCTMD, adding that she strongly endorses the use of them for SCAD patients.

In the editorial, Tweet and Olin say the study does not make clear why only 76% of patients were on beta-blockers. They also point out that the dosage and type of beta-blocker were not specified.

Saw responded that it is not uncommon for the largely young and female SCAD population to refuse or be nonadherent to beta-blockers due to side effects.

“A lot of clinicians are a bit reluctant to use beta-blockers . . . because of lack of prior data and because these are often young, otherwise healthy individuals,” Saw said. “I would hope this study would send a message that there is some data that you can reduce your risk of recurrent tear, and I think this should also push us forward to collect more prospective data on this cohort of patients. Ideally, we should have randomized trials, but [given that] the overall frequency of this disease is relatively rare, it would be hard to do one that would be of substantial size and give us more definitive answers.”

Emphasis on Need for Prevention, More Data

Tweet and OIin also question the hypertension data in the study, pointing out that no information is given about whether blood pressure was under optimal control, how long the patient had hypertension, or what types of medications they were taking.

“Without knowledge of these details, it is not possible to assess exactly what role hypertension played in the rate of recurrence,” they write.

Furthermore, Tweet and Olin say while the hypertension and beta-blocker association cannot be “accepted as absolute fact” without randomized data, the study may help spur more attention to preventative strategies, which could include cardiac rehabilitation, stress modification, limitation of extreme activities, and anxiety/depression treatment.

“Further research is necessary to risk-stratify patients, including identification of anatomical and genetic markers that may confer risk,” they conclude.