Approach to Acute Myocardial Infarction Cardiogenic Shock with Dr. Venu Menon

With the advent and rapid evolution of contemporary percutaneous coronary intervention (PCI), the early invasive management of acute myocardial infarction (AMI) has become a mainstay in therapy with significant impact on patient outcomes. However, despite modern advances in technology and system-based practices, AMI presenting with cardiogenic shock (CS) continues to portend a high risk of morbidity and mortality. Few randomized controlled clinical trials are available to guide decision-making in this uniquely challenging patient population.

Understanding the pathophysiologic mechanism by which injury occurs and propagates the shock cycle can be instrumental in selecting an appropriate strategy for revascularization and left ventricular unloading.

In this episode we are joined by Dr. Venu Menon, The Mehdi Razavi Endowed Chair and Professor of Medicine at the Cleveland Clinic Lerner College of Medicine, section head of clinical cardiology, fellowship program director, and director of the Cardiac intensive care unit at the Cleveland Clinic. Dr. Menon shares his wealth of knowledge and experience to help us review the contemporary data available for AMI CS management in a case-based discussion.

We are also joined by Dr. Priya Kothapalli, star chief fellow and future interventionalist from University of Texas at Austin, series co-chair Dr. Yoav Karpenshif, and CardioNerds co-founders Amit Goyal and Daniel Ambinder.

Audio editing by CardioNerds Academy Intern, Dr. Christian Faaborg-Andersen.

Pearls and Quotes

1. The H&P does matter! Age, location of infarction, heart rate, systolic blood pressure, and heart failure symptoms all carry weight in determining prognosis and risk of mortality.

2. Define functional status, comorbid conditions, and life expectancy to help guide clinical decision-making. Do a quick bedside echocardiogram, if possible, to elucidate the predominant mechanism driving CS and rule out mechanical complications.

3. Act with urgency! Get to the catheterization lab to characterize coronary anatomy and revascularize the culprit vessel as soon as possible.

4. Minimize/avoid the use of vasopressors; if needed, wean as quickly as possible to avoid worsening myocardial ischemia. Consider mechanical circulatory support early!

5. Despite dramatic advances in AMI management, data is limited in AMI CS management. Ask the important questions, get involved in the scientific inquiry as a trainee!

Show Notes

1. Why is it important to recognize AMI complicated by CS?
• AMI CS occurs in 7-10% of patients presenting with AMI and has a higher prevalence among elderly patients.
• The SHOCK trial (1999) showed significant survival benefit at 6 months with early revascularization with balloon angioplasty compared to medical therapy alone in AMI CS.
• Registry data suggests that early revascularization is beneficial in AMI CS even in elderly patients. Decision-making should be guided using a holistic view of the patient’s overall biology.
• Despite advances in revascularization techniques and availability of mechanical support, AMI CS portends a 40-45% risk of 30-day mortality in the modern era.
• Significant variation in management strategy exists between centers and data to guide decision-making is limited.
• The Society for Cardiovascular Angiography and Intervention (SCAI) classification system of shock stage may be helpful in characterizing patient risk and guiding clinical decision-making.

2. Which patients with AMI CS should undergo invasive monitoring and revascularization? What should be the timing of any intervention?
• In viable patients presenting with AMI CS, the primary goal should be to get to the catheterization laboratory to characterize the anatomy and revascularize the culprit vessel as soon as possible.
• Patient history, physical exam, laboratory exam, and echocardiography, if available, are critical pieces of information that should be obtained without delaying catheterization laboratory transfer.
• Patients presenting in SCAI shock stages C-E may require stabilization pre-procedure while minimizing delays to revascularization.
• Anticipating potential sequelae (such as acute pulmonary edema with respiratory failure requiring intubation) is crucial to minimizing delays.
• Maintain adequate perfusion pre-procedure (goal mean arterial blood pressure of >65mmHg). Minimize use and avoid escalation of vasopressor or inotropic therapy, as these agents worsen myocardial ischemia.
• The prevalence of multivessel disease, left main or proximal left anterior descending artery disease in AMI CS is high. Revascularization with restoration of TIMI 3 flow as soon as possible should be the primary goal, regardless of strategy.

3. When should mechanical circulatory support (MCS) be used in AMI CS?
• Immediate MCS may be beneficial in patients with persistent hemodynamic or electrical instability or patients at high risk for developing instability. MCS should be placed early and maintained until the shock cycle is reversed.
• If the primary mechanism for CS is left ventricular failure, an intra-aortic balloon pump (IABP) or transvalvular axial flow pump (Impella) may be considered. Additional strategies include venoarterial extracorporeal membrane oxygenation with left ventricular venting strategy or TandemHeart percutaneous assist device.
• There is limited data regarding the role of MCS in AMI; this is an area of active clinical investigation. Mechanistically, MCS provides the obvious benefits of supporting systemic perfusion while reducing cardiac workload; risks include bleeding, thrombosis, hemolysis, limb ischemia, and other vascular complications.
• MCS should be weaned slowly using multiple clinical and hemodynamic parameters, including Swan Ganz catheter data.
• If unable to wean MCS due to insufficient myocardial recovery despite support over a prolonged period in the setting of adequate revascularization, additional options such as durable MCS, heart transplantation, or palliative care should be considered.

4. What is the current evidence base for culprit-only vs. complete revascularization in AMI CS?
• The CULPRIT-SHOCK trial showed an increased 30-day and 1-year risk of a composite of all-cause mortality and need for renal replacement therapy in patients that underwent culprit and immediate non-culprit vessel revascularization in AMI CS.
• While there is no definitive data to support complete revascularization in AMI CS, this strategy may be considered in patients with multiple possible culprit lesions or subtotal non-culprit lesions with reduced TIMI grade flow corresponding with wall motion abnormality and normal wall thickness suggestive of viable myocardium.

References

1. Tehrani BN, Truesdell AG, Psotka MA, et al. A Standardized and Comprehensive Approach to the Management of Cardiogenic Shock. JACC Hear Fail. 2020;8(11):879-891. doi:10.1016/j.jchf.2020.09.005
2. Kapur NK, Davila CD. Timing, timing, timing: the emerging concept of the ‘door to support’ time for cardiogenic shock. Eur Heart J. 2017;38(47):3532-3534. doi:10.1093/eurheartj/ehx406
3. Hochman JS, Sleeper LA, Webb JG, et al. Early Revascularization in Acute Myocardial Infarction Complicated by Cardiogenic Shock. N Engl J Med. 1999;341(9):625-634. doi:10.1056/NEJM199908263410901
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9. Thiele H, Akin I, Sandri M, et al. PCI Strategies in Patients with Acute Myocardial Infarction and Cardiogenic Shock. N Engl J Med. 2017;377(25):2419-2432. http://www.nejm.org/doi/10.1056/NEJMoa1710261. Accessed April 10, 2021.
10. Van Diepen S, Katz JN, Albert NM, et al. Contemporary Management of Cardiogenic Shock: A Scientific Statement from the American Heart Association. Circulation. 2017;136(16):e232-e268. doi:10.1161/CIR.0000000000000525
11. Henry, Timothy D., et al. “Invasive Management of Acute Myocardial Infarction Complicated by Cardiogenic Shock: A Scientific Statement from the American Heart Association.” Circulation, vol. 143, no. 15, 2021, doi: 10.1161/cir.0000000000000959.