Robert S. Schwartz, MD, FACC,FAHA
Director, Pre-Clinical Research
Minneapolis Heart Institute Foundation
Are there alternatives to invasive coronary angiograms?
Dr. Hauser's clinical interests include management of cardiac
arrhythmias, and he is a founder and past president of the
prestigious North American Society of Pacing and Electrophysiology
(NASPE). His research has resulted in multiple patents related
to cardiac pacing, defibrillation, and electrophysiology.
Cardiovascular disease is the number one cause of morbidity
and mortality in developed and developing nations worldwide.
Coronary plaque has many microscopic forms including hard
calcified plaque, dense or loose fibrous tissue, necrotic
regions, inflammation, and lipid pools. Plaques can create
stenosis (narrowing), total occlusions (blockage), or
“vulnerable plaques” with a propensity to rupture and develop
sudden thrombosis. No prior technology, whether invasive
or noninvasive, can characterize coronary artery plaque.
Great excitement is developing around Computed Tomographic
Angiography (CTA), a method for visualizing the coronary
arteries using fast CT machines. Current powerful scanners
can now visualize even small plaques in the coronary arteries
of living patients, and do so minimally invasively, using
only a peripheral intravenous contrast injection.
CTA is evolving very rapidly since scanners with multi-slice
capacity have been available since 2002 (16-slice machines),
and now improved using 64-Slice CT Scanners. Spatial resolution
of 0.4-0.5 mm and temporal resolution of 160 millisecond
can noninvasively visualize coronary stenosis (lumen size)
and also the artery wall and plaque. This is a key development
since soft, non-obstructive plaque is an important cause
of heart attack.
Will CT replace invasive coronary angiograms? Definitive
answers are emerging. To some extent, it already has. The
CTA imaging group at the Minneapolis Heart Institute (under
the direction of Dr. John Lesser) has shown that CTA accuracy
can determine if an abnormal stress test is a “true positive” or
not, avoiding invasive coronary angiography to determine
coronary anatomy. CTA has already replaced some invasive
diagnostic angiography at MHI, and may eventually replace
most of these procedures. We believe CTA will help redefine
the catheterization laboratory role, sending only patients
needing invasive procedures to the cath lab. Patients coming
to the cath lab will have known coronary anatomy, and the
interventionalist will have an optimal interventional treatment
plan, having reviewed the CTA images beforehand.
CTA thus represents an exciting new technology to assess,
diagnose and plan the optimal treatment for patients. Rapid
technology advances will, we believe, revolutionize the diagnosis
of coronary artery disease within the next 2-3 years.
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