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Spontaneous coronary artery dissection (SCAD) is often followed by adverse events, but conservative treatment with beta blockers appeared protective, according to a single-center study.

In a group of 327 nonatherosclerotic SCAD patients, all presented with an MI (three-quarters had non-ST-segment elevation MI) and were largely treated medically at first. The majority left the hospital on aspirin and beta blockers, which they kept taking over 3 years' follow-up. Only 16.5% and 2.2% got percutaneous coronary intervention [PCI] and coronary artery bypass grafting, respectively.

During that 3 year period, , reported Jacqueline Saw, MD, of Vancouver General Hospital, and colleagues in the Aug. 29 issue of the Journal of the American College of Cardiology. Those events included:

• Recurrent MI 16.8%
• Recurrent de novo SCAD 10.4%
• Revascularization 5.8%
• Death 1.2%
• Stroke 1.2%

Recurrent SCAD was tied to hypertension (adjusted HR 2.46, 95% CI 1.23-4.93) but less likely with beta blocker use (HR 0.36, 95% CI 0.18-0.73).

"It would appear, therefore, that beta-blockers would be the preferred antihypertensive class in patients with SCAD and secondary agents should be considered to ensure achievement of optimal blood pressure goals, but that will require further study," Saw's group said.

"The acute and long-term management of SCAD remains contentious as there have been no randomized controlled trials [RCTs] assessing optimal treatment strategy. Experts in the field endorse a conservative (nonrevascularization) treatment strategy for acute SCAD lesions without high-risk features, given the suboptimal acute PCI outcomes and the tendency for SCAD lesions to heal spontaneously."

"Only 3.3% of conservatively treated patients had subsequent extension of dissection and required unplanned revascularization in-hospital. Thus, the low in-hospital complication rate observed with primarily a conservative approach in our cohort supported the expert recommendations," the investigators concluded.

Yet, "there is no information about whether the patients' blood pressure was under optimal control, the types of medications each patient was taking, or the duration of hypertension. Without knowledge of these details, it is not possible to assess exactly what role hypertension played in the rate of recurrence," countered Marysia S. Tweet, MD, of Mayo Clinic College of Medicine in Rochester, Minn., and Jeffrey W. Olin, DO, of Icahn School of Medicine at Mount Sinai in New York.

Not studied in Saw's analysis, coronary tortuosity may also contribute to coronary dissection susceptibility, Tweet and Olin wrote in an .

"Before these factors can be accepted as absolute fact, a multicenter RCT to test these hypothesis-generating findings is needed."

Included in the study were nonatherosclerotic SCAD patients (n=327) who presented at Vancouver General Hospital, a high-volume referral center. Participants were an average 52.5 years old (56.9% postmenopausal); 90.8% were women; and 82.0% were white.

For long-term follow-up, they were prospectively enrolled in the Non-Atherosclerotic Coronary Artery Disease or Canadian SCAD registries.

Of the majority (80.7%) who got screening for cerebrovascular, renal, and iliac fibromuscular dysplasia with CT angiography or catheter angiography, a quarter had SCAD that was deemed idiopathic.

However, fibromuscular dysplasia turned out to be the most common predisposing factor by far (62.7%), followed by systemic inflammation (11.9%), having had at least five pregnancies (11.9%), and use of hormonal therapy at the time (11.6%).

"Although these arteriopathies are suspected to weaken the coronary arteries, making them more susceptible to dissections, there is no coronary histological proof to confirm a direct causal link," Saw and colleagues commented.

SCAD patients at their center commonly reported triggers, with potential emotional and physical stressors preceding the index SCAD 48.3% and 28.1% of the time, respectively.

They are routinely advised to limit weight-bearing activities to 30 lb and to avoid competitive sports, according to Saw's group. In addition, the hospital has a dedicated SCAD cardiac rehabilitation center offering psychosocial support.

"However, there is no clinical trial evidence that limiting such triggers will reduce risk of recurrent SCAD," the authors acknowledged.

Aside from the nonrandomized study design, their analysis suffered from incomplete screening for fibromuscular dysplasia (and with different imaging modalities) and a low event rate for recurrent SCAD. Residual confounders in multivariable analysis could be excluded, either.