The CardioNerds Cardiology Case Reports series shines light on the hidden curriculum of medical storytelling. We learn together while discussing fascinating cases in this fun, engaging, and educational format. Each episode ends with an “Expert CardioNerd Perspectives & Review” (E-CPR) for a nuanced teaching from a content expert. We truly believe that hearing about a patient is the singular theme that unifies everyone at every level, from the student to the professor emeritus.
We are teaming up with the ACC FIT Section to use the #CNCR episodes to showcase CV education across the country in the era of virtual recruitment. As part of the recruitment series, each episode features fellows from a given program discussing and teaching about an interesting case as well as sharing what makes their hearts flutter about their fellowship training. The case discussion is followed by both an E-CPR segment and a message from the program director.
A woman in her late 40s presented with a one day history of intermittent chest pain. EKG showed anteroseptal and lateral STE with reciprocal ST depressions in the inferior leads. High-sensitivity troponin was elevated at 333 ng/mL. Emergent LHC showed a long and narrow left main with areas of additional contrast filling into a false lumen with no flow in the LAD. RCA and LCx were normal appearing (make sure you check out the angiogram videos below!). IVUS showed dissection and heavy thrombus burden in the left main artery. Shortly after the diagnostic angiogram, the patient went into V-fib arrest and received one shock with ROSC. Amiodarone was started and an Impella CP was placed for additional left ventricular support. ECMO and emergent CABG were not readily available at this time so the interventional team attempted revascularization with PCI to the left main given patient’s hemodynamic instability from ongoing ischemia. However, even after PCI to left main, flow to LAD remained poor and the LCx now also appeared occluded. The decision was made to cease further attempts at revascularization. Unfortunately, post-procedure TTE showed a reduced EF of 22% with anterior and anterolateral hypokinesis. She was transferred to CCU on maximal Impella support. Patient eventually developed acute renal and liver failure secondary to cardiogenic shock and suffered an additional V-fib arrest with ROSC. Eventually, Ronald Reagan UCLA was contacted for transfer and the mobile ECMO team was dispatched. They placed the patient on VA-ECMO in the outside facility and transferred her to Ronald Reagan UCLA. At Ronald Reagan, revascularizationwas attempted given persistent cardiogenic shock and 3 stents were successfully deployed in the LAD. She was eventually weaned off of both Impella and ECMO after successful PCIs to LAD. However, TTE showed persistently low EF and patient eventually underwent successful heart-kidney transplantation.
Case Media
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A. ECG: Anterior STE, STE in I/aVL but depressedions in V4-V6, inferior reciprocal ST depression B. X-ray of explanted heart shows stents extending from LM -> dLAD C. Cross-section of explanted heart from apex to base showing infarct in the anteroseptal area D. Histological cross section of the explanted LAD.
This film shows slit like LM with no LAD. High OM/RI and LCx look ok.
BMW wire used to cross distal LM into high OM/RI Arrested after diagnostic, got ROSC and then Impella CP inserted L femoral
Attempting wiring the true lumen, stuck in mLAD after 1st septal comes off
IVUS from RI to LM. Shows dissection plane and lots of thrombus LM IVUS details: 4.57 x 5.0mm proximally, 4.52mm distally
Unable to pass a wire into mid LAD
PCI of LM: Synergy 4.0 x 16mm DES deployed in LM and post-dilated with Emerge NC 4.5 x 8mm balloon
Flow remained poor at mLAD even after PCI to LM
LCx system closed after LM PCI, so no further attempts
TTE: Apical 4 Chamber
TTE: Apical 2 Chamber
TTE: Apical 3 Chamber
LCx occluded with large OM1/Ramus still patent
Post PCI of the LAD
Episode Schematics & Teaching
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The CardioNerds 5! – 5 major takeaways from the #CNCR case
What is SCAD and what population is most at risk?
SCAD stands for spontaneous coronary artery dissection. It is an acute coronary event and is defined as a spontaneous separation of the coronary artery wall that is not iatrogenic or related to trauma. It is an important cause of acute myocardial infarction.
Women comprise 87%-95% of SCAD patients with a mean age of presentation between 44-53 years, just like the patient in this case. The “typical” SCAD patient is a middle-aged female with few traditional cardiovascular risk factors such as hypertension, hyperlipidemia, and tobacco use. However, our understanding of a “typical” SCAD patient is limited as the majority of patients in large series have been white and it is likely that patients of different ethnic and racial backgrounds have been under-represented in most current registries.
In some studies, the prevalence of SCAD appears around 4% of all patients presenting with ACS and up to 35% in women 50 years or under presenting with ACS.
Pregnancy associated SCAD is an important subset of patients. It can occur at any time during the pregnancy or post-partum, with the majority of cases occurring postpartum. SCAD associated with pregnancy tends to have a more severe clinical presentation, including left main involvement, multi-vessel dissection and cardiogenic shock. Both pregnancy and non-pregnancy associated SCAD tend to occur more frequently in multiparous women and those that report a higher prevalence of pre-eclampsia.
What are the two hypotheses that have been proposed to explain the pathophysiology of SCAD?
Before reviewing the pathophysiology, let’s briefly review the coronary arterial wall structure. The intima is the inner layer in contact with the intraluminal space. In normal vasculature, the intima is only a few cell layers thick and is separated from the media by the internal elastic lamina. The media is the middle layer and is made up of layers of smooth muscle cells which help regulate vascular tone. The media is separated from the adventitia by the external elastic lamina. Finally, the adventitia surrounds the media and through fibrous connective tissue provides support for the epicardial vessel.
In SCAD, a hematoma forms within the tunica media separating the intima or intima/media from the vessel and compressing the true lumen leading to ischemia. There are several proposed hypotheses for how this occurs:
“Inside-out” hypothesis: an endothelial-intimal disruption or “flap” develops first and then blood enters the sub-intimal space from the true lumen via this “flap”
“Outside-in” hypothesis: a hematoma forms within the media, possibly from disruption of traversing micro-vessels, and compresses and occludes the true lumen as the hematoma expands.
In both hypotheses, the end result is separation of the layers of coronary artery wall, creating a false vs. true lumen. Currently, the evidence favors the “outside-in” theory because in most SCAD cases, there are no communication between the true and false lumens observed.
What are the angiographic appearances of SCAD?
Left anterior descending artery is the most commonly affected vessel in SCAD.
There are three classifications of SCAD based on angiographic appearance (the Yip-Saw classification).
Type 1: Contrast dye staining of the arterial wall demonstrates double or multiple radiolucent lumens separated by a radiolucent flap. There may be dye “hang-up” or slow contrast clearing.
Type 2: This is the most common subtype. It is characterized by long, diffuse, and smooth narrowing that can vary from mild stenosis to complete occlusion, often with abrupt changes in lumen diameter.
Type 2a SCAD demonstrates normal arterial segments proximal and distal to a dissection and does not extend into a distal vessel.
Type 2b does extend into the distal tip of a vessel.
Type 3: The angiographic appearance mimics a focal stenosis of atherosclerotic disease and typically requires intracoronary imaging to make a definitive diagnosis.
There are other angiographic findings that may clue the cardiology team into a diagnosis of SCAD. SCAD tends to affect more distal segments than atherosclerotic disease. Furthermore, the left anterior descending (LAD) artery is the most commonly affected vessel in SCAD. Patients with SCAD tend to have more tortuous vessels and atherosclerotic lesions are usually absent from vessels not affected by the SCAD. Some reports have indicated the external luminal compression by the intramural hematoma (IMH) gives the appearance of a stick insect.
What is the management of SCAD in the acute setting?
As Dr. Hayes et al. note in their JACC review, the focus in the acute setting is to restore perfusion and maintain myocardial function as conservatively as possible rather than on how to restore normal coronary architecture as in atherosclerotic ACS. The use of thrombolytics have resulted in extension of dissection or hematoma and should be avoided. Diagnostic left heart catheterization is recommended but outcomes of PCI in SCAD are less predictable. There are often technical challenges due to the fragility of the vessel wall, instrumentation can propagate a dissection or occlude distal branches, and long-stents may be required as SCAD lesions tend to be extensive and in small distal vessels. Temporal resolution of the IMH may lead to late stent mal-apposition as the IMH reabsorbs.
CABG is typically only considered if PCI has failed or in high risk lesions. Again, the fragility of the vessels makes a successful result challenging. Identifying the true lumen (for graft anastomosis) may be difficult. Sutures may not hold and patients may be prone to anastomotic complications. Over the long-term, healing of the native coronaries may lead to bypass graft failure due to competitive flow into the native system. However, CABG can still be an effective measure to stabilize unstable patients.
Among patients treated conservatively, 95% of patients usually will heal within 30 days; therefore, if there is no ongoing ischemia or hemodynamic instability, instrumentation should be avoided.
In terms of medications, patients with LV dysfunction should receive GDMT (with special attention to teratogenic medications for patients that are pregnant or breastfeeding) and patients undergoing PCI should receive DAPT. In patients that do not receive PCI, the evidence and expert opinion is varying on whether DAPT should be recommended for medical management of ACS.
What’s the long-term management and outcomes for patients with SCAD?
SCAD can be associated with underlying systemic arteriopathy such as fibromuscular dysplasia (FMD) in >50% cases and head/neck aneurysms in 7-11% cases. Patients diagnosed with SCAD should undergo CTA or MRA from head to pelvis to identify additional extra-coronary vascular abnormalities.
Post-SCAD chest pain is common and may occur for many months following the index episode. There can be various triggers of the chest pain, including exercise, stress, or during the menstrual period. Given the increased risk of iatrogenic catheter-induced dissection in post-SCAD patients, a multi-modal evaluation is recommended before considering repeat LHC (e.g., ECG, biomarkers, echo, coronary CTA, stress imaging).
Rates of recurrent SCAD have been reported as 10 to 30%. Secondary prevention for SCAD include avoidance of potential triggers such as stress or extreme exertion and blood pressure control. However, cardiac rehabilitation and moderate exercise’s benefits likely outweigh the theoretical risk of recurrent SCAD with exertion. Beta-blockers may decrease the risk of recurrence but evidence is limited.
There are important considerations for future pregnancy and SCAD. See the JACC review for more details! Another important aspect of post-SCAD care is recognizing the high burden of psychological distress amongst SCAD patients. Clinicians must recognized this early and provide early treatment and appropriate referrals to ensure recovery.
It sounds like the benefits of E-CPR remain to be further elucidated. Are there any specific features that help predict who would benefit from ECPR?
While we do not have high quality randomized data, observational data in EPCR has shown that shorter no flow times (i.e., CPR initiated within 5 minutes of arrest), total duration of CPR <60 minutes, intermittent return of spontaneous circulation, an initial shockable rhythm, and lower serum lactate concentration have been associated with increased survival with better neurologic recovery.
A well-known protocol is the University of Minnesota ECPR protocol (transport with ongoing CPR to the cardiac catheterization laboratory for ECPR) for patients with refractory VT/VF arrest. The inclusion and exclusion criteria for this protocol included
Inclusion: (1) OHCA with presumed cardiac etiology cardiac arrest; (2) first presenting rhythm is shockable (VF or VT); (3) Age 18 to 75 years; (4) Received at least 3 direct current (DC) shocks without sustained ROSC; (5) received Amiodarone 300 mg; (6) Body can accommodate a Lund University Cardiac Arrest System (LUCA) automated CPR device; and (7) Transfer time from the scene to the Cardiac Catheterization Lab of < 30 minutes
Exclusion: (1) ROSC before 3 shocks were delivered; (2) Nursing home residents: (3) DNR/DNI orders; (4) known terminal illness (e.g., malignancy); (5) Traumatic arrest; (6) PEA or asystole; (7) significant bleeding; (8) manual CPR as the only option
Using this strict UMN-ECPR protocol, Bartos et al. retrospectively compared 160 consecutive adult patients with refractory VT/VF arrest treated with ECPR to 654 patients treated with conventional CPR from the amiodarone arm of the ALPS study (Amiodarone, Lidocaine or Placebo study). They found ECPR had favorable survival compared with conventional CPR at each CPR duration interval <60 minutes; however, longer CPR duration was associated with worsening neurologic outcomes and survival in both groups. There remains considerable evidence gaps to define which patient populations would most benefit from this intensive resource.
