Am J Cardiovasc Dis 2012;2(1):xxx-xxx
Original Article
Tachycardic vs. pharmacologic stress myocardial perfusion imaging:
differential implications in multi-vessel ischemia
Thanh H Nguyen, John D Horowitz, Steven A Unger
Departments of Cardiology1 and Nuclear Medicine2, The Queen Elizabeth Hospital, the University of Adelaide, Adelaide,
Australia.
Received October 31, 2011; accepted November 19, 2011; Epub January 1, 2012; published January 15, 2012
Abstract: Background: In patients unable to exercise, potential methods of induction of reversible myocardial ischemia
include physiological heart rate acceleration via pacing or dobutamine infusion and asymmetric coronary vasodilatation
using dipyridamole. Although their bases for induction of ischemia are widely disparate, no direct comparison of these
techniques has previously been reported. Methods: We performed a randomised, paired comparison of dipyridamole and
pacing myocardial perfusion imaging (MPI) in 28 patients in whom exercise stress imaging was precluded, comparing the
detection, localisation and quantitation of ischemia. Results: Reversible myocardial ischemia was detected in 21 patients,
concordantly in 13 (p = 0.042). There was a high degree of concordance (p < 0.0001) regarding locations of sites of
ischemia. While there was a good correlation (r = 0.74, p < 0.0001) between size of total ischemic zones with dipyridamole
and pacing, the magnitude of ischemia tended to be greater with dipyridamole (mean percentage of left ventricular
my¬ocardium ± SD, 9.4 ± 11.0% vs. 7.0 ± 9.0%, p = 0.091). Furthermore, this difference resulted from accentuation of the
primary ischemic zone with dipyridamole in pa¬tients with multi-vessel ischemia (mean ± SD, 28.1 ± 21.1% vs. 18.7 ±
16.1%, p = 0.046). Conclusions: Despite major differences in mechanism(s) of induction of ischemia, dipyridamole and
pacing produce similar results regarding detection, localisation and severity of ischemia. However, dipyridamole
accentuates ischemia in primary (vs. sec¬ondary) ischemic zones, consistent with known induction of coronary “steal”.
This should be taken into account in interpretation of scan results. (AJCD1110002).
Keywords: Dipyridamole, pacing, myocardial perfusion imaging, coronary “steal”
Full Text PDF
Address all correspondence to:
Dr. Steven A Unger
The Queen Elizabeth Hospital, 28 Woodville, SA 5011, Australia.
Phone: +61-8-82226431
Fax: +61-8-82226038
Email: steven.unger@health.sa.gov.au
Original Article
Tachycardic vs. pharmacologic stress myocardial perfusion imaging:
differential implications in multi-vessel ischemia
Thanh H Nguyen, John D Horowitz, Steven A Unger
Departments of Cardiology1 and Nuclear Medicine2, The Queen Elizabeth Hospital, the University of Adelaide, Adelaide,
Australia.
Received October 31, 2011; accepted November 19, 2011; Epub January 1, 2012; published January 15, 2012
Abstract: Background: In patients unable to exercise, potential methods of induction of reversible myocardial ischemia
include physiological heart rate acceleration via pacing or dobutamine infusion and asymmetric coronary vasodilatation
using dipyridamole. Although their bases for induction of ischemia are widely disparate, no direct comparison of these
techniques has previously been reported. Methods: We performed a randomised, paired comparison of dipyridamole and
pacing myocardial perfusion imaging (MPI) in 28 patients in whom exercise stress imaging was precluded, comparing the
detection, localisation and quantitation of ischemia. Results: Reversible myocardial ischemia was detected in 21 patients,
concordantly in 13 (p = 0.042). There was a high degree of concordance (p < 0.0001) regarding locations of sites of
ischemia. While there was a good correlation (r = 0.74, p < 0.0001) between size of total ischemic zones with dipyridamole
and pacing, the magnitude of ischemia tended to be greater with dipyridamole (mean percentage of left ventricular
my¬ocardium ± SD, 9.4 ± 11.0% vs. 7.0 ± 9.0%, p = 0.091). Furthermore, this difference resulted from accentuation of the
primary ischemic zone with dipyridamole in pa¬tients with multi-vessel ischemia (mean ± SD, 28.1 ± 21.1% vs. 18.7 ±
16.1%, p = 0.046). Conclusions: Despite major differences in mechanism(s) of induction of ischemia, dipyridamole and
pacing produce similar results regarding detection, localisation and severity of ischemia. However, dipyridamole
accentuates ischemia in primary (vs. sec¬ondary) ischemic zones, consistent with known induction of coronary “steal”.
This should be taken into account in interpretation of scan results. (AJCD1110002).
Keywords: Dipyridamole, pacing, myocardial perfusion imaging, coronary “steal”
Full Text PDF
Address all correspondence to:
Dr. Steven A Unger
The Queen Elizabeth Hospital, 28 Woodville, SA 5011, Australia.
Phone: +61-8-82226431
Fax: +61-8-82226038
Email: steven.unger@health.sa.gov.au
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