NEW YORK, May 23 (Reuters Health) - Magnetic resonance imaging (MRI) can
detect the re-narrowing of heart arteries that often occurs months after a
person undergoes the artery-clearing procedure angioplasty. Use of MRI can
therefore spare many patients from having to undergo angiography, a procedure
that includes an injection of dye to outline the coronary arteries.
Among patients who undergo successful procedures to restore normal blood
flow to the heart, between 25% and 60% can experience re-narrowing (or
restenosis) of the artery that was opened, according to Dr. W. Gregory Hundley
from Wake Forest University Baptist Medical Center in Winston-Salem, North
Carolina, and associates.
Until now, most individuals who have chest pain in the months after
angioplasty would have had to undergo angiography to determine whether
restenosis had occurred. MRI may offer a noninvasive alternative for assessing
such patients, the authors report in the May 23rd issue of the journal
Circulation: Journal of the American Heart Association.
The investigators compared MRI and angiography results in 17 patients who
experienced chest pain more than 3 months after a successful procedure to
relieve a blocked artery.
The MRI test was used to measure blood flow to the heart, the researchers
explain, then they injected a drug that increases the heart rate to the point
where it must work harder, and measured blood flow to the heart again. The
relative blood flow is a measure of how narrowed a heart artery may be.
On average, the MRI evaluation took just under 1 hour, but the time spent in
the MRI machine proved worthwhile, Hundley and colleagues note. The results were
quite comparable to those found with angiography.
Depending upon the cutoff values used, MRI was able to detect between 82%
and 100% of the artery narrowings, the report indicates. If the MRI result
suggested narrowing, the angiography confirmed restenosis between 89% and 100%
of the time.
The authors conclude that MRI can be used to detect functionally important
narrowings of the coronary arteries in patients who experience chest pain weeks
to months after a successful procedure to open a coronary artery.
"The value of MRI, in addition to being non-invasive, is that it tells us
how a narrowed artery affects the heart during activity," said Hundley in a
statement. "It goes beyond measuring the size of the narrowing to tell us
whether the body is getting enough oxygen-rich blood."
In addition, co-author Dr. Kerry Link suggested that MRI "can also be used
in seemingly healthy people to detect vessel disease in time to prevent heart
attacks or angina."
