SCAI 2021: Selected Topics From Featured Clinical Research

By George W. Vetrovec, MD, MACC
Editorial Team Lead, Invasive Cardiovascular Angiography & Interventions collection on
Richmond, VA

The Society for Cardiovascular Angiography & Interventions (SCAI) 2021 Scientific Sessions presented important updates and new science with effective presentations and discussions despite the challenges of the online format. The knowledge presented was useful, but the loss of personal interactions was a limitation.

There were multiple presentations covering coronary disease management, structural, pediatric/congenital, and peripheral. It's impossible to cover everything, but we have selected several presentations that cover a spectrum of critical issues. I trust you will find this helpful, and, as always, comments are appreciated.

Update on the NACMI Registry
By George W. Vetrovec, MD, MACC
Editorial Team Lead, Invasive Cardiovascular Angiography & Interventions collection on
Richmond, VA

Quick Takes

  • The North American COVID-19 Myocardial Infarction (NACMI) registry is a multicenter database of US and Canadian coronavirus disease 2019 (COVID-19)-positive patients and patients under investigation who present with ST-segment elevation myocardial infarction (STEMI). The registry was developed to better understand COVID-19-related apparent STEMI presentations.
  • This updated analysis of the COVID-19-positive STEMI population reveals more frequent atypical symptoms on presentation, more frequent diabetes mellitus, and more ethnic minorities. No culprit lesion was identified in 23% of patients.
  • Mortality for COVID-19-positive patients was 33% with older age, shock, diabetes mellitus, and presentation while in hospital all being predictors of death.
  • Successful primary percutaneous coronary intervention (PCI) was achieved in a large majority of COVID-19-positive patients, with usually expected door-to-balloon times associated with lower mortality.

The NACMI registry is a joint endeavor of the American College of Cardiology, SCAI, and the Canadian Association of Interventional Cardiology to better understand characteristics of STEMI presentations occurring in patient with COVID-19. This update of STEMI representations includes 305 COVID-19-positive patients and 521 patients under investigation from the United States with 26 COVID-19-positive patients and 124 patients under investigation from Canada. A matched (by age and sex) control group of over 600 patients was developed from STEMI patients pre-COVID-19 (2015-2019).

Thrombolytic management was rare in the COVID-19-positive patients (<3%). However, 20% of COVID-19-positive patients did not receive an angiogram. Reasons included unknown, conservative management, various forms of carditis and COVID-19-related severe respiratory illness. Of patients undergoing coronary angiography, 71% underwent primary PCI, and 23% did not receive PCI because no culprit lesion was identified (both p < 0.001 compared to controls). The primary outcome (defined as in-hospital death, stroke, recurrent myocardial infarction, and repeat, unplanned revascularization) occurred in 36% of COVID-19-positive patients compared to 5% in controls (p < 0.001 compared to the control population).

In summary, COVID-19-positive STEMI patients have unique characteristics with frequent non-culprit lesions and increased risk for adverse outcomes despite accepted primary PCI treatment times (door to balloon). Future analyses of larger populations should allow more specific data on the differences of these patients in presentation and risk to hopefully increase understanding and lead to specialized treatment strategies and improved outcomes.

Comparison of Patients Undergoing PCI in Contemporary US Practice to the ISCHEMIA Trial Population
By Robert F. Riley, MD, MS, FACC
Overlake Medical Center
Bellevue, WA

Quick Takes

  • Only 32.3% of patients undergoing PCI for stable coronary artery disease (CAD) in a contemporary analysis of the National Cardiovascular Data Registry (NCDR) CathPCI registry would have met inclusion for ISCHEMIA (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches).
  • Higher-risk patients undergoing PCI who would have been excluded from ISCHEMIA represent a significant proportion of patients undergoing revascularization in modern catheterization laboratories.
  • Expanded efforts focused on training and clinical studies/trials directed specifically toward caring for this patient population are warranted.

The recent release of data from ISCHEMIA comparing optimal medical therapy (OMT) plus PCI to OMT alone for patients with stable CAD with significant ischemia on noninvasive testing challenged many long-held beliefs about the benefits of PCI in non-acute coronary syndromes. Hard clinical endpoints did not significantly differ between the groups at long-term follow-up, though quality-of-life metrics were improved in the invasive compared to the conservative group.

However, there is often a significant difference between the outcomes achieved during clinical trials and those obtained once these data are applied to clinical practice. In order to evaluate the applicability of ISCHEMIA data to a contemporary, real-world US population, Dr. Saurav Chatterjee and colleagues performed a cross-sectional analysis of the NCDR CathPCI registry from October 2017 to June 2019 to identify patients undergoing PCI. They then stratified the segment of patients who underwent PCI for stable CAD into four groups:

  • ISCHEMIA-like (would have met inclusion criteria)
  • Not ISCHEMIA-like due to high-risk features
  • Not ISCHEMIA-like due to lack of significant ischemia (negative or low-risk findings on preprocedural stress testing or negative invasive physiologic assessment)
  • Those without enough data to be classifiable

They found that only 32.3% of 388,212 patients who underwent PCI for stable CAD during the study period would have met inclusion criteria to be included in the trial (ISCHEMIA-like), with notable heterogeneity across reporting institutions. Additionally, they compared unadjusted in-hospital outcomes between the four groups and noted that the ISCHEMIA-like cohort had the lowest in-hospital mortality, and the not ISCHEMIA-like, higher-risk cohort had a significantly increased mortality rate compared to the other groups.

One possible explanation for the lack of similarity between those included in ISCHEMIA and modern-day patients undergoing PCI may be that practice in the United States had already started to favor conservative medical therapy over aggressive revascularization practices for less-complex, stable CAD during the decade it took to enroll in ISCHEMIA (based on prior data from other trials). This is suggested by the data showing that 58.1% of PCI in the CathPCI registry during the study period were for acute coronary syndromes, cardiogenic shock (CS), and cardiac arrest, and 18.5% of PCI for stable CAD were for higher-risk patients ("not ISCHEMIA-like due to high-risk features"); notably, both populations would have been excluded from ISCHEMIA. Therefore, although ISCHEMIA provided excellent data in shaping care for one part of our ischemic CAD population, there remains a need for continued clinical investigation and education in the expanding complex and higher-risk PCI (complex and high-risk coronary intervention, or "CHIP") space because an increasing number of our patients may be becoming "not ISCHEMIA-like."

The National Cardiogenic Shock Initiative
By Lorenzo Azzalini, MD, FACC
VCU Health Pauley Heart Center & Virginia Commonwealth University
Richmond, VA

Francesco Moroni, MD
VCU Health Pauley Heart Center & Virginia Commonwealth University
Richmond, VA

Quick Takes

  • Mortality due to acute myocardial infarction (AMI) and CS remains high and has largely remained unchanged in the last few decades.
  • The National Cardiogenic Shock Initiative (NCSI) has shown that implementation of a standardized protocol focusing on prompt identification of shock, rapid establishment of mechanical circulatory support (MSC), and use of right-heart catheterization to guide subsequent management can significantly improve AMICS survival compared to previously reported outcomes.

CS remains among the most lethal acute cardiovascular conditions in contemporary practice and has traditionally carried in-hospital mortality rates exceeding 40%. The most common etiology of CS is AMI. The introduction of primary PCI in CS secondary to myocardial infarction (AMICS) in the late 1990s has greatly improved the outcomes of shock patients. However, since then no treatment or therapeutic strategy has been shown to significantly alter the prognosis of AMICS patients. In recent years, the development and widespread availability of effective MCS devices beyond intra-aortic balloon pump (IABP) has sparked new interest in AMICS and has fostered the development of novel approaches to the treatment of shock patients.

The NCSI is a single-arm, prospective, multicenter study that evaluated the impact of a standardized treatment algorithm incorporating early MCS and invasive hemodynamic assessment on the outcomes of patients presenting with AMICS and treated with PCI. The study enrolled 406 AMICS patients at 73 centers in the United States between 2016 and 2020. Patients who did not undergo PCI and those with active bleeding, IABP implantation before arrival, mechanical complications of AMI, unwitnessed or prolonged cardiac arrest upon presentation, or any contraindication to MCS were excluded from the NCSI. All subjects underwent early MCS using a percutaneously inserted transaortic microaxial pump (Impella [Abiomed; Danver, MA]) upon AMICS confirmation. After MCS insertion, primary PCI was performed. Invasive hemodynamic evaluation by right-heart catheterization was performed in >90% of patients and was used to guide subsequent management. Baseline and outcome findings of the NCSI study showed the following:

  • Mean age of AMICS patients was 64 ± 12 years, and 82% of AMICS were due to ST-segment elevation myocardial infarction. Eighty-five percent of patients were supported with inotropes or pressors at the time of enrollment. Seventeen percent experienced out-of-hospital cardiac arrest, 27% in-hospital cardiac arrest, and 9% were under active cardiopulmonary resuscitation at the time of MCS insertion.
  • Approximately one-third of AMICS patients presented in SCAI CS stage E (i.e., patients deteriorating on multiple supports or who are experiencing cardiac arrest with ongoing cardiopulmonary resuscitation). SCAI CS stage E patients were more commonly diabetic (51% vs. 27%; p = 0.01) but had no other differences in terms of baseline comorbidities compared with subjects presenting with lesser stages of shock (stages C/D).
  • Median door-to-MCS and door-to-balloon times were 78 and 81 minutes, respectively. However, time to symptom onset or time from shock onset were not reported. Of note, 33% of patients were not in shock at the time of presentation.
  • Two-thirds of patients had multivessel disease. Of note, 39% of subjects underwent multivessel PCI during the index procedure. Thrombolysis in Myocardial Infarction 3 flow on the culprit vessel was achieved in 91% of cases. Thrombectomy devices were used in 27% of cases, which is in line with the IABP SHOCK II (Intraaortic Balloon Pump in Cardiogenic Shock II) reported outcomes and may indicate a high thrombotic burden or inadequate platelet antagonization. The latter possibility has particular relevance because the majority of antiplatelet medications currently employed are orally administered and might not be effectively when absorbed by a hypoperfused gastrointestinal system.
  • Thirty-day survival was 68%, which appears to be significantly higher in comparison to other contemporary CS studies, including the SHOCK (One-Year Survival Following Early Revascularization for Cardiogenic Shock) trial (53%), the IABP SHOCK II (60%) and the CULPRIT-SHOCK (Culprit Lesion Only PCI Versus Multivessel PCI in Cardiogenic Shock) trial (49%). Interestingly, the SCAI CS stage on presentation was a major determinant of 30-day survival, with patients in SCAI CS stages C/D having significantly better survival rates compared to SCAI CS stage E (77% vs. 49%; p < 0.01).

The overall findings of the NCSI are consistent with a clinically relevant survival improvement among AMICS patients, when standardized shock management protocols are employed, compared with prior literature. The cardinal features of the approach developed by the NCSI investigators follow:

  • Prompt identification of AMICS and rapid implementation of treatment. Although no comprehensive data on the duration of chest pain and of shock are provided, the fact that at least one third of patients were not in shock at presentation points toward very short latency between shock onset and MCS. Indeed, the 80 minutes of median door-to-support time is an impressive result.
  • Immediate establishment of MCS.
  • Systematic use of invasive hemodynamics to guide patient management.

Although the results are impressive, further studies are needed to validate this model of care. A hub-spoke network for the management of shock patients is strongly advocated to warrant rapid access to state-of-the-art care. Moreover, more granular data on right-heart catheterization before and after MCS/PCI are needed to gather in-depth insights that can inform further initiatives to improve the outcomes of this sick patient population (e.g., escalation of left-sided support or addition of right-sided support).

Short-Term Mortality in CS Using the SCAI Classification System: The Evidence Mounts
Behnam N. Tehrani, MD, FACC
Inova Heart and Vascular Institute
Falls Church, VA

Carolyn Rosner, NP, MBA
Inova Heart and Vascular Institute
Falls Church, VA

Shashank S. Sinha, MD, MSc, FACC
Inova Heart and Vascular Institute
Falls Church, VA

Quick Takes

  • The SCAI classification system for CS is highly predictive of in-hospital and 30-day mortality across the severity spectrum and varying phenotypes associated with this lethal syndrome.
  • It is anticipated that the new update to the SCAI classification system to be presented at 2021 SCAI SHOCK Virtual Conference will inform research strategies to address current gaps in clinical knowledge.

At the SCAI 2021 Scientific Sessions, Dr. Jacob Jentzer and colleagues presented their research findings examining clinical outcomes in CS as a function of the SCAI classification system. The authors cited 14 publications with more than 15,000 patients with diagnosis of CS.1-7 The registries included in this study were diverse and included patients with both AMI and heart failure (HF) from the Mayo Clinic, the Cardiogenic Shock Working Group, the NCSI, the Critical Care Cardiology Trials Network, the University Heart Centre Hamburg, Sentara Heart Hospital, and King's College Hospital. Notably, only one study3 was prospective, and no randomized clinical trials were included. Using a number of variables, including clinical, laboratory, and hemodynamic parameters, seven distinct definitions of the SCAI CS stages were observed. Despite a wide range of prevalence for each SCAI CS stage within the respective registries, an incremental rise in in-hospital and 30-day mortality was observed with higher SCAI staging, albeit varied based on CS definition and the study population:

  • A = 1-5%
  • B = 0-34%
  • C = 11-54%
  • D = 24-68%
  • E = 42-77%

These findings were consistent across both the AMICS and HF CS phenotypes. Factors independently associated with reduced survival at each SCAI stage included older age, cardiac arrest, deteriorating hemodynamics, abnormal echocardiogram findings, vasoplegia, and acute kidney injury.

The authors are to be commended for presenting this timely and burgeoning research in CS. Building on their seminal consensus statement first published in 2019, there are several key takeaways from this comprehensive review:

  • CS is a hemodynamically complex and multifaceted syndrome with a wide spectrum of clinical and hemometabolic manifestations8,9
  • A common lexicon to facilitate clear and consistent identification and communication of disease severity may be used in a conjunction with multidisciplinary and protocol-based care to improve short-term outcomes in CS.
  • Although no randomized controlled trial data are currently available, complete hemodynamic profiling is associated with improved outcomes and may lead to more timely disease recognition, escalation of therapies, and implementation of tailored treatment strategies.10
  • Congestion is an important independent marker of risk in CS, and it may serve as an additional target for hemodynamically tailored medical and device-based therapies.4
  • In the modern era, HF CS is the predominant shock phenotype, and it is associated with greater biventricular congestion and a more indolent clinical presentation compared to AMICS.11,12
  • SCAI CS staging is not meant to be used as a snapshot in time, but rather should be reassessed serially because it may provide useful prognostic information and guide treatment beyond the time of index diagnosis.
  • In addition to standardized nomenclature, sound clinical judgement, multidisciplinary team-based care, and standardized risk stratification with historically validated clinical factors may be used to inform decision-making strategies around patient selection and MCS.13,14
  • Utilizing the standard nomenclature of the SCAI classification system to facilitate identification and risk assessment, concerted efforts should be made to develop regionalized shock networks predicated on interhospital collaboration and expedited transfer to high-volume CS centers with American Heart Association Level 1 cardiovascular intensive care units capable of providing around-the-clock hemodynamic monitoring and multi-organ system care.15

Potential opportunities for further research with this taxonomy include assessment of its prognostic utility at 1 year and beyond, integration with molecular phenotyping strategies using biomarkers to predict risk, and incorporation into machine learning and artificial intelligence strategies to further enhance disease recognition.16 It is anticipated that the new update to the classification system that will be presented at the 2021 SCAI SHOCK Virtual Conference in October will continue to inform strategies to address these knowledge gaps.

Socioeconomic and Geographic Access to Novel Therapeutics: An Analysis of Growth in TAVR Programs
By George W. Vetrovec, MD, MACC
Editorial Team Lead, Invasive Cardiovascular Angiography & Interventions collection on
Richmond, VA

Quick Takes

  • Studies have documented inequities in transcatheter aortic valve replacement (TAVR) access by geographic location. This presentation addresses how geography and economics impact new TAVR programs.
  • An analysis of 554 new TAVR programs between 2012 and 2018 revealed 543 (98%) were in metropolitan areas (>50,000 residents), with 293 (53%) having existing programs. Only 11 new TAVR programs were in non-metropolitan areas.
  • TAVR programs were more likely to be established in hospitals whose patients were characterized by fewer patients who qualify for both Medicare and Medicaid, higher median incomes, and fewer distressed community indices.
  • Thus, new TAVR programs tend to be more duplicative in areas with existing TAVR programs in which socioeconomically advantaged patients exist.

In addition, these factors resulted in fewer TAVR procedures per 100,000 Medicare beneficiaries in areas with more Medicaid dual-eligible patients, lower average median household incomes, and more average community distress.

Factors affecting these findings are complicated by the realities of hospital funding. Starting an expensive program such as TAVR with a low predicted volume in a rural area may exceed the financial capability of a hospital that is further restrained by Medicare cost-of-living adjustments for rural hospitals, potentially reducing overall reimbursement in general in addition to the actual TAVR programs. TAVR programs are expensive because of new, specialized equipment and require multiple specialists for performance of the procedures, which may not otherwise exist in these hospitals. Furthermore, poorer-funded, rural hospitals may serve as safety net hospitals with higher numbers of Medicaid patients, further complicating funding for new technology programs.

Although not mentioned by the presenters, there is also a quality concern related to developing and maintaining physician and staff competency considering lower procedure volumes, which may affect "second" hospitals in an already well-served metropolitan area as well as in lower-volume, rural hospitals. The authors plan to identify the roles of race and ethnicity as they may apply to inequitable access to TAVR. In addition, they plan to identify patient-level barriers to TAVR access and evaluate potential solutions to overhaul systems contributing to inequitable care.


  1. Jentzer JC, van Diepen S, Barsness GW, et al. Cardiogenic Shock Classification to Predict Mortality in the Cardiac Intensive Care Unit. J Am Coll Cardiol 2019;74:2117-28.
  2. Schrage B, Dabboura S, Yan I, et al. Application of the SCAI classification in a cohort of patients with cardiogenic shock. Catheter Cardiovasc Interv 2020;96:E213-E219.
  3. Baran DA, Long A, Badiye AP, Stelling K. Prospective validation of the SCAI shock classification: Single center analysis. Catheter Cardiovasc Interv 2020;96:1339-47.
  4. Thayer KL, Zweck E, Ayouty M, et al. Invasive Hemodynamic Assessment and Classification of In-Hospital Mortality Risk Among Patients With Cardiogenic Shock. Circ Heart Fail 2020;13:e007099.
  5. Hanson ID, Tagami T, Mando R, et al. SCAI shock classification in acute myocardial infarction: Insights from the National Cardiogenic Shock Initiative. Catheter Cardiovasc Interv 2020;96:1137-42.
  6. Jentzer JC, Schrage B, Holmes DR, et al. Influence of age and shock severity on short-term survival in patients with cardiogenic shock. Eur Heart J Acute Cardiovasc Care 2021;Jan 4:[Epub ahead of print].
  7. Lawler PR, Berg DD, Park JG, et al. The Range of Cardiogenic Shock Survival by Clinical Stage: Data From the Critical Care Cardiology Trials Network Registry. Crit Care Med 2021;49:1293-302.
  8. Esposito ML, Kapur NK. Acute mechanical circulatory support for cardiogenic shock: the "door to support" time. F1000Res 2017;6:737.
  9. Baran DA, Grines CL, Bailey S, et al. SCAI clinical expert consensus statement on the classification of cardiogenic shock: This document was endorsed by the American College of Cardiology (ACC), the American Heart Association (AHA), the Society of Critical Care Medicine (SCCM), and the Society of Thoracic Surgeons (STS) in April 2019. Catheter Cardiovasc Interv 2019;94:29-37.
  10. Garan AR, Kanwar M, Thayer KL, et al. Complete Hemodynamic Profiling With Pulmonary Artery Catheters in Cardiogenic Shock Is Associated With Lower In-Hospital Mortality. JACC Heart Fail 2020;8:903-13.
  11. Hernandez-Montfort J, Sinha SS, Thayer KL, et al. Clinical Outcomes Associated With Acute Mechanical Circulatory Support Utilization in Heart Failure Related Cardiogenic Shock. Circ Heart Fail 2021;14:e007924.
  12. Harjola VP, Lassus J, Sionis A, et al. Clinical picture and risk prediction of short-term mortality in cardiogenic shock. Eur J Heart Fail 2015;17:501-9.
  13. Rab T, Kern KB, Tamis-Holland JE, et al. Cardiac Arrest: A Treatment Algorithm for Emergent Invasive Cardiac Procedures in the Resuscitated Comatose Patient. J Am Coll Cardiol 2015;66:62-73.
  14. Pöss J, Köster J, Fuernau G, et al. Risk Stratification for Patients in Cardiogenic Shock After Acute Myocardial Infarction. J Am Coll Cardiol 2017;69:1913-20.
  15. 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:e232-e268.
  16. Iborra-Egea O, Rueda F, García-García C, Borràs E, Sabidó E, Bayes-Genis A. Molecular signature of cardiogenic shock. Eur Heart J 2020;41:3839-48.

Clinical Topics: Invasive Cardiovascular Angiography and Intervention

Keywords: Acute Coronary Syndrome, Acute Kidney Injury, Aged, Algorithms, American Heart Association, Artificial Intelligence, Benchmarking, Biomarkers, Cardiac Catheterization, Chest Pain, Clinical Reasoning, Consensus, Conservative Treatment, Contraindications, Control Groups, Coronary Angiography, Coronary Artery Disease, COVID-19, Critical Care, Cross-Sectional Studies, Diabetes Mellitus, Ethnic Groups, Follow-Up Studies, Heart Arrest, Hemodynamic Monitoring, Heart Failure, Hemodynamics, Hospital Mortality, Hospitals, Hospitals, Rural, Intensive Care Units, Laboratories, Machine Learning, Medicaid, Medicare, Myocardial Infarction, Myocarditis, Patient Care Team, Patient Selection, Percutaneous Coronary Intervention, Phenotype, Physicians, Prevalence, Prognosis, Prospective Studies, Quality of Life, Reference Standards, Registries, Registries, Research Design, Risk Assessment, Safety-net Providers, Severity of Illness Index, Shock, Cardiogenic, Shock, Cardiogenic, Socioeconomic Factors, Specialization, ST Elevation Myocardial Infarction, Stroke, Survival Rate, Technology, Technology, Pharmaceutical, Transcatheter Aortic Valve Replacement, Universities, Vasoplegia

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