By Jeffrey Zimmet, MD, PhD

Associate Professor of Medicine, University of California, San Francisco; Director, Cardiac Catheterization Laboratory, San Francisco VA Medical Center

Dr. Zimmet reports no financial relationships relevant to this field of study.

SYNOPSIS: In the largest study to date about patients with spontaneous coronary artery dissection who underwent follow-up angiography, 95% of those who underwent repeat cath more than 30 days later showed spontaneous angiographic healing.

SOURCE: Hassan S, Prakash R, Starovoytov A, Saw J. Natural history of spontaneous coronary artery dissection with spontaneous angiographic healing. JACC Cardiovasc Interv 2019; Feb. 22. pii: S1936-8798(18)32479-8. doi: 10.1016/j.jcin.2018.12.011. [Epub ahead of print].

Although it is uncommon, spontaneous coronary artery dissection (SCAD) is an increasingly recognized cause of acute myocardial infarction (MI). Because of underdiagnosis, the true prevalence is unknown. The authors of prior studies have reported this condition in 0.1-4.0% of patients presenting with acute coronary syndrome. However, the authors of a more recent study of MI in women < 60 years of age with improved angiographic recognition of SCAD reported that this condition was the cause of MI in up to 24-35% of such cases. Currently, upon recognition of an acute SCAD event, medical therapy is recommended as first-line therapy, except in the cases involving ongoing ischemia, hemodynamic instability, or dissection of the left main coronary artery. Prior studies of angiographic follow-up in SCAD have been small and have used inconsistent definitions of angiographic healing.

Hassan et al examined patients in two prospective SCAD registries (the Non-Atherosclerotic Coronary Artery Disease registry and the Canadian SCAD study) who had undergone repeat invasive coronary angiography. Of 404 total SCAD patients, 202 underwent repeat angiograms after the initial event. Forty-six of these had undergone percutaneous coronary intervention (PCI), leaving 156 conservatively managed patients for the analysis, with a total of 182 noncontiguous SCAD lesions. Characteristics of the patients mirrored prior reports of SCAD. Most patients were younger (mean age, 51.5 ± 8.7 years), 88.5% were women, and 75.6% also had received diagnoses of extra-coronary fibromuscular dysplasia. All had presented with MI, with 77.6% represented by non-ST-segment elevation MI. Nearly 70% of cases involved type 2 angiographic SCAD, defined as diffuse smooth narrowing that can vary in severity. A little more than one-quarter of patients exhibited the more-classic appearance of type 1 SCAD, showing contrast dye staining of the arterial wall with multiple lumens. A total of 46.7% of lesions had less than TIMI grade 3 flow, with 40 cases showing TIMI grade 0 flow. The median angiographic stenosis severity was 79%.

All patients in this study underwent repeat invasive angiography, with median time to repeat imaging of 154 days (interquartile range, 70-604 days). Spontaneous angiographic healing was observed in 157 of 182 lesions. Of the 25 lesions that did not meet criteria for healing, 17 underwent the repeat angiographic study < 30 days from the index SCAD event. At follow-up, only 10 of the 182 lesions had less than TIMI grade 3 flow. Of the 40 lesions with initial TIMI grade 0 flow, 35 had improved to TIMI grade 3 flow at follow-up. The authors concluded that in conservatively managed SCAD lesions, the overwhelming majority heal spontaneously when imaged more than 30 days from the index event.

COMMENTARY

In this largest-yet retrospective cohort of SCAD patients with available angiographic follow-up, more than 95% of lesions examined more than 30 days after the index event met criteria for spontaneous angiographic healing. This supports the current recommendations for conservative first-line management of SCAD patients (when clinically feasible). It is interesting to note that so many patients in this study were successfully managed this way. For example, the 22% of patients in this cohort who presented with ST elevation MI were successfully treated without revascularization. Likewise, although nearly half of included lesions and vessels had less-than-normal flow (and 40 of them had TIMI grade 0 flow), conservative management still was undertaken based on the patient’s clinical status at the time, with PCI undertaken only for cardiogenic shock, ongoing ischemia, sustained ventricular arrhythmia, or left main involvement.

The recommendation for conservative management comes in part from the complexity of PCI in patients with SCAD, including a historically high complication rate that can include failure to wire the true lumen and propagation of the dissection proximally and distally. The findings of this study support this general recommendation, showing that patients who complete successful conservative management most often also demonstrate spontaneous healing of the artery over time.

However, this recommendation comes with caveats. Cardiologists should examine each case individually and manage in the most appropriate manner. Among the current cohort of patients, all of whom were treated at a high-volume center with significant experience with SCAD, 46 of the 202 with repeat angiograms were excluded because they had undergone clinically indicated PCI. Follow-up information shows that clinical event rates were high even among patients who showed evidence of angiographic healing (35% had recurrent MIs, 6.7% underwent revascularization, 2% suffered stroke, and 1.5% died). Although the upfront recommendation is for conservative therapy when possible, these patients are complex, and management requires an open mind.