Highlights from #ASNC2020 – A FIT’s Perspective

• By: admin
• On: 11/16/2020 03:16:05
• In: Annual Meeting

A Glimpse into the Future: Machine Learning, AI and Wearable Devices
Innovation was a central theme at ASNC2020. The plenary session on cardiac applications of artificial intelligence (AI) in wearable devices was chaired by Rami Doukky, MD, FASNC. Mintu Turakhia, MD from the Stanford Health Center delved into several integrations of digital monitoring, AI and medicine. Wearable devices are now available to measure a battery of different parameters including electrocardiogram, electroencephalogram, oximeter, pressure and temperature recordings. From the cardiology standpoint, heart rate and rhythm monitoring are the most commonly encountered. There are a host of different devices available.  However, robust validation and regulatory approval have hindered their widespread use in clinical practice. “Wearables” have moved beyond “wellness” and into rhythm assessment as a pre-diagnostic and diagnostic tool. Important questions raised were how reliable are the data collected and does data collection even have a benefit. Nonetheless, there are advantages which need to be recognized. AI will allow for the “democratization” of medicine and facilitate access to care, an imperative asset especially in underserved regions. Soon, the assimilation of digital and telehealth will lead to an era of automated healthcare and cardiologists should be at the forefront of this revolution.
 
Amyloidosis – Best Practices
With the development of novel agents for the treatment of TTR amyloidosis which prolong life, there has been an increased interest in diagnosing this disease, once thought incurable.  Nuclear cardiology has been on the forefront of this change and the utilization of Tc^99m PYP imaging to facilitate diagnosis has increased exponentially over the past 5-7 years. The release of the Expert Consensus Recommendations for Multimodality Imaging in Cardiac Amyloidosis¹ in 2019 is expected to bring more uniformity in acquisition, reporting and interpretation of these scans.
 
When there is clinical suspicion and in the presence of typical imaging features on either echocardiography, PET or CMR, Tc^99m PYP imaging should be used in conjunction with free light chain testing to diagnose cardiac amyloidosis. Though endomyocardial biopsy is no longer required for diagnosis, it is also not obsolete. Biopsies should be employed in negative or equivocal scans where clinical suspicion is high. They may also be used in the setting of elevated free light chains or monoclonal gammopathy coupled with a positive scan. It is imperative to recognize potential sources of error during Tc^99m PYP imaging and be familiar with the steps needed to mitigate these. These include ordering the test in the appropriate clinical scenario, the correct interpretation of light chain testing and the utilization of SPECT to confirm myocardial uptake.
 
The plenary session ended with a talk by ASNC President, Sharmila Dorbala, MD, MPH, MASNC, who discussed the use of PET imaging in cardiac amyloidosis. Though its utility has been seen in AL amyloidosis and can even detect early stages of cardiac involvement, TTR amyloidosis remains a data free zone. There are important future perspectives such as the utility of follow-up imaging for response to therapy and protocols to screen asymptomatic allele carriers.
 
Cardiac PET is here to stay
The application of PET imaging is growing. Albert Sinusas, MD, FASNC, demonstrated the utility of PET in the management of atrial and ventricular arrhythmias. These include assessing the size of an infarct, the extent of myocardial inflammation and autonomic dysfunction. Molecular guidance during catheter ablation has been utilized for peri-infarct ablation in ventricular tachycardias (VT) and aide decision making to ablate the ganglionic plexi for atrial fibrillation. The evaluation of myocardial blood flow heterogeneity has been used to predict VT in patients with hypertrophic cardiomyopathy.
 
Calcium Scoring and the #PowerOfZero
This was a joint session with the Society of Cardiovascular Computed Tomography (SCCT) on clinical applications of the coronary artery calcium (CAC) score moderated by Joao Vitola MD PhD MASNC. Both sides of the calcium score spectrum were discussed. Ron Blankstein MD, FASNC, discussed management of asymptomatic patients with a CAC > 1,000. These patients have high event rates and should be considered for high-risk secondary prevention therapies. Lifestyle modification is the mainstay. Blood pressure management and aspirin for secondary prevention are helpful. Aggressive LDL-C lowering may be pursued with high intensity statins in combination with ezetimibe, PCSK9 inhibitors  and possibly the newly introduced bempedoic acid ². If triglycerides are elevated > 135, icosapent ethyl may be prescribed ³. Lipoprotein (a) is known to be atherogenic and treatments targeting this molecule are currently under investigation. If these patients are asymptomatic, no further ischemic evaluation is necessary however if uncertain about symptoms, an exercise treadmill stress test may be considered. If symptoms are present, PET myocardial perfusion imaging with myocardial blood flow reserve is the best validated tool to assess for ischemia.
 
On the other hand, Khurram Nasir, MD, asked thought-provoking questions about the integration of CAC with MPI. He explored whether CAC can be a gatekeeper for ischemia testing and demonstrated the #PowerOfZero and how a CAC of 0 has a negative predictive value of 99%, thereby allowing for better patient selection. In addition, CAC when combined with SPECT may improve diagnostic interpretation for obstructive CAD.
 
 
Life After the ISCHEMIA Trial
There are many lessons to be learnt from the ISCHEMIA trial⁴. Lawrence Philips, MD, FASNC, highlighted the importance of good compliance with optimal medical therapy in order to reproduce the trial's results. In patients with angina at baseline, patients in the early invasive strategy arm had significant improvement in angina control and quality of life QoL via the Seattle Angina Questionnaire summary score. Prem Soman, MD, PhD, MASNC, emphasized that non-invasive stress testing is still very relevant as the trial was not an imaging trial but a randomized trial of treatment allocation after ischemia and CAD had been established. However, the trial does underscore the importance of “whom to image” as much as “how to image”. Nuclear cardiology is able to identify high risk features beyond just ischemia and still maintains a central role in diagnosis and risk stratification. 
 
 
Selecting Between Different Functional Tests
Viviany Taqueti MD, FASNC discussed the role of ischemia testing in patients with non-obstructive CAD with an emphasis on CMR versus PET. She gave an excellent talk on coronary microvascular dysfunction (CMD) which is prevalent in ~50% of symptomatic patients, 2/3^rd of whom are women. CMD is associated with a worse prognosis even for a CAC score of zero. Unfortunately, evidence-based therapy for CMD is still lacking.

Marcelo Di Carli MD, MASNC, spoke on the strengths and limitations of “lesion specific” ischemia versus “myocardial” ischemia. Lesion specific ischemia measurement with fractional flow reserve (FFR) is a simple concept that is easy to obtain in the cath lab and has been validated in randomized control trials and thus accepted in practice guidelines. However, it does not take into account factors other than focal stenosis including diffuse CAD and CMD. It also cannot define the extent of ischemia in the coronary bed and its accuracy is diminished in the setting of severe CMD. This is explained by the increased vascular resistance limiting maximal vasodilatation which leads to reduced flow (and thereby ischemia) while reducing the pressure drop across a stenosis. This results in a “pseudo-normalizing” FFR. On the other hand, myocardial ischemia testing is widely available, can localize the culprit territory, and can provide prognostic data. When combined with blood flow quantification, it is a powerful non-invasive diagnostic tool. The PACIFIC trial demonstrated that quantitative PET is the most accurate approach for CAD evaluation ⁵. The integration of non-invasive and intra-coronary functional testing for ischemia provides synergistic information that allow defining the extent of ischemia while attributing ischemic myocardium to a specific coronary stenosis that can facilitate decision making.
 
Is Multimodality Imaging Training Way Forward for Cardiovascular Imaging?
Karthikeyan (Karthik) Ananthasubramaniam, MD, FASNC, made a compelling argument for the adoption of a “cardiovascular imaging rotation” by cardiology fellowship programs rather than rotating in “silos” of echo, nuclear or CT. This shift reflects the changing landscape of cardiology with an increasing emphasis on cardiac CT and MRI in daily practice and also promotes a patient-centered approach.  He also highlighted the pitfalls of the “numbers” based training in current practice as it is an oversimplification of competency. Though not accredited by the ACGME, there are currently about 60 advanced cardiovascular imaging fellowships in the U.S. As a fellow-in-training, I look forward to the integration of multi-modality imaging into the cardiology fellowship curriculum.
 
In conclusion, ASNC2020 was a fantastic educational experience. This was amplified by the social media team led by ASNC2020 Social Media Chair Niti Aggarwal, MD, FASNC, and assisted by ASNC Social Media Task Force Committee Chair Renée Bullock-Palmer, MD, FASNC. Each session had a virtual moderator who live tweeted the highlights from the session. Speakers would often engage with attendees on Twitter and answer questions, thus shrinking the virtual divide. There were a total of 13 million impressions made by the #ASNC2020 and #CVNuc hashtags, ensuring knowledge dissemination to all parts of the globe.

Did you miss any of the ASNC2020 sessions? Don't worry. We've got you covered. The Meeting OnDemand (MOD) sessions are available through October 2021 (login first to access).
 
References
 
1.           Dorbala S, Ando Y, Bokhari S, et al. ASNC/AHA/ASE/EANM/HFSA/ISA/SCMR/SNMMI Expert Consensus Recommendations for Multimodality Imaging in Cardiac Amyloidosis: Part 1 of 2-Evidence Base and Standardized Methods of Imaging. J Card Fail. 2019;25(11):e1-e39.
2.           Ray KK, Bays HE, Catapano AL, et al. Safety and Efficacy of Bempedoic Acid to Reduce LDL Cholesterol. New England Journal of Medicine. 2019;380(11):1022-1032.
3.           Bhatt DL, Steg PG, Miller M, et al. Cardiovascular Risk Reduction with Icosapent Ethyl for Hypertriglyceridemia. New England Journal of Medicine. 2018;380(1):11-22.
4.           Maron DJ, Hochman JS, Reynolds HR, et al. Initial Invasive or Conservative Strategy for Stable Coronary Disease. New England Journal of Medicine. 2020;382(15):1395-1407.
5.           Driessen RS, Danad I, Stuijfzand WJ, et al. Comparison of Coronary Computed Tomography Angiography, Fractional Flow Reserve, and Perfusion Imaging for Ischemia Diagnosis. Journal of the American College of Cardiology. 2019;73(2):161.

Read Emmanuel Akintoye's ASNC2020 FIT Blog

Read more blogs from the ASNC Social Media Task Force