Category: Cardiac Imaging

One-Stop Cardiac CT

Posted on by Jake Fishman

A new Radiology Journal study found that combining Triple-rule-out CT (TRO CT) with Late Contrast Enhancement CT (LCE CT) significantly improves acute chest pain diagnosis.

Background – It’s traditionally been challenging to diagnose patients with acute chest pain and mild troponin rise, as TRO CT is effective for several key diagnoses (coronary artery disease, acute aortic syndrome, pulmonary embolism) but can’t identify nonvascular causes of myocardial injury.

The Study – The researchers examined 84 troponin-positive patients with acute chest pain using TRO CT, and then performed LCE CT exams on the 42 patients who had negative/inconclusive results. 

The Results – The added LCE CT exams revealed positive/conclusive findings in 34 of the 42 previously-negative/inconclusive patients (including 22 w/ myocarditis), improving overall diagnostic rates from 50% to 90% (from 42/84 to 76/84).

The Takeaway – This new TRO CT + LCE CT protocol could make cardiac CT a “one-stop shop” for diagnosing acute chest pain, eliminating the need for follow-up MRI exams and allowing faster diagnoses. That’s especially notable considering that CT is already recommended for patients with low-risk acute chest pain (to exclude CAD) and was recently proposed as a gatekeeper for invasive coronary angiography.

Chest Pain Imaging Guidance

Posted on by Jake Fishman

If it seemed like coronary imaging folks were more excited than usual last week, it’s because the AHA/ACC’s long-awaited chest pain guidelines just set the stage for a lot more imaging.

The Guidelines – The American Heart Association (AHA) and the American College of Cardiology (ACC) released their first clinical guidelines for the assessment and diagnosis of chest pain, outlining a range of new standards, processes, and pathways, while giving coronary imaging a central diagnostic role.

Front-Line Coronary CTA – The new guidelines made coronary CTA a front-line coronary artery disease test, assigning CCTA their highest recommendation level and proposing it for a large group of patients (mid-high risk of CAD, stable chest pain, <65yrs).

FFRct Next in Line – HeartFlow’s FFRct analysis will often serve as the next diagnostic step when CCTA exams reveal obstructive CAD (40-90% stenosis) or are inconclusive, with FFRct results either clarifying diagnosis or supporting treatment decisions. 

Stress Imaging Pathways – The AHA/ACC guidelines also gave stress imaging (e.g. TTE, echo, CMRI, PET, etc.) their highest recommendation level, positioning stress imaging for more serious cases (likely or confirmed obstructive CAD, ≥65yrs) as well as for diagnosing myocardial ischemia and estimating risks of major cardiac events among patients with less severe cases (intermediate risk, no known CAD, acute chest pain).

Takeaway – These new guidelines are a big deal for coronary imaging, given the millions of people who show up at US emergency departments with chest pain each year. It’s also going to require some big changes across EDs, imaging centers, and radiology departments/practices, who will have to retool their imaging protocols/fleets and be able to expertly interpret a wave of coronary imaging exams (and handle a wave of incidentals).

Silent Atherosclerosis

Posted on by Jake Fishman

A new study in Circulation used coronary CTA scans and CAC scoring to reveal a surprisingly high prevalence of “silent” coronary artery atherosclerosis in the general population, suggesting that this could “lay the foundation” for future CT-based cardiac screening programs.

The Study – The researchers analyzed CCTA and CAC exams from 25k randomly recruited Swedish participants (50-64yrs, none w/ known coronary heart disease) finding that:

  • 42% had CCTA-detected atherosclerosis
  • 8.3% had noncalcified plaques
  • 5.2% had significant stenosis
  • 1.9% had serious coronary artery diseases
  • All participants with >400 CAC scores had atherosclerosis (yes, 100%), and 45.7% had significant stenosis
  • Some participants with 0 CAC scores had atherosclerosis (5.5%) and significant stenosis (0.4%)
  • So, CAC-based screening might still miss some at-risk patients

The Takeaway – 2021 brought a notable surge in academic and business efforts focused on CT-based cardiac screening, and this study’s revelation about “silent” atherosclerosis in the general population suggests that cardiac screening’s momentum will continue.

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