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Mechanism of decreased sensitivity of dobutamine associated left ventricular wall motion analyses for appreciating inducible ischemia in older adults.

Vasu S, Little WC, Morgan TM, Stacey RB, Ntim WO, Hamilton C, Thohan V, Chiles C, Hundley WG - J Cardiovasc Magn Reson (2015)

Bottom Line: Dobutamine associated left ventricular (LV) wall motion analyses exhibit reduced sensitivity for detecting inducible ischemia in individuals with increased LV wall thickness.This study was performed to better understand the mechanism of this reduced sensitivity in the elderly who often manifest increased LV wall thickness and risk factors for coronary artery disease.These findings provide insight as to why dobutamine associated wall motion analyses exhibit reduced sensitivity for identifying inducible ischemia in elderly.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal medicine, Section on Cardiology, Wake Forest School of Medicine, Winston Salem, North Carolina, 27157, USA. svasu@wakehealth.edu.

ABSTRACT

Background: Dobutamine associated left ventricular (LV) wall motion analyses exhibit reduced sensitivity for detecting inducible ischemia in individuals with increased LV wall thickness. This study was performed to better understand the mechanism of this reduced sensitivity in the elderly who often manifest increased LV wall thickness and risk factors for coronary artery disease.

Methods: During dobutamine cardiovascular magnetic resonance (DCMR) stress testing, we assessed rate pressure product (RPP), aortic pulse wave velocity (PWV), LV myocardial oxygen demand (pressure volume area, PVA, mass, volumes, concentricity, and the presence of wall motion abnormalities (WMA) and first pass gadolinium enhanced perfusion defects (PDs) indicative of ischemia in 278 consecutively recruited individuals aged 69 ± 8 years with pre-existing or known risk factors for coronary artery disease. Each variable was assessed independently by personnel blinded to participant identifiers and analyses of other DCMR or hemodynamic variables.

Results: Participants were 80% white, 90% hypertensive, 43% diabetic and 55% men. With dobutamine, 60% of the participants who exhibited PDs had no inducible WMA. Among these participants, myocardial oxygen demand was lower than that observed in those who had both wall motion and perfusion abnormalities suggestive of ischemia (p = 0.03). Relative to those with PDs and inducible WMAs, myocardial oxygen demand remained different in these individuals with PDs without an inducible WMA after accounting for LV afterload and contractility (p = 0.02 and 0.03 respectively), but not after accounting for either LV stress related end diastolic volume index (LV preload) or resting concentricity (p = 0.31-0.71).

Conclusions: During dobutamine stress testing, elderly patients experience increased LV concentricity and declines in LV preload and myocardial oxygen demand, all of which are associated with an absence of inducible LV WMAs indicative of myocardial ischemia. These findings provide insight as to why dobutamine associated wall motion analyses exhibit reduced sensitivity for identifying inducible ischemia in elderly.

Trial registration: This study was registered with Clinicaltrials.gov (NCT00542503).

No MeSH data available.


Related in: MedlinePlus

Discordance between left ventricular wall motion abnormalities and perfusion defects indicative of inducible myocardial ischemia. Cine white blood imaging end-diastolic (left panel) and end-systolic (middle panel) frames from slice position acquired in the middle of the left ventricle at peak dobutamine and atropine infusion administered to achieve >80% of the maximum predicted heart rate response for age. The white arrows indicate normal wall motion of the posterior and lateral wall segments. However, in the right panel, a first pass gadolinium enhanced perfusion image also acquired at peak stress is displayed. The yellow arrows indicate a hypoperfused region of the LV myocardium consistent with inducible ischemia. This participant underwent contrast coronary angiography which demonstrated a >70% stenosis of the saphenous vein graft to the right coronary artery.
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Fig1: Discordance between left ventricular wall motion abnormalities and perfusion defects indicative of inducible myocardial ischemia. Cine white blood imaging end-diastolic (left panel) and end-systolic (middle panel) frames from slice position acquired in the middle of the left ventricle at peak dobutamine and atropine infusion administered to achieve >80% of the maximum predicted heart rate response for age. The white arrows indicate normal wall motion of the posterior and lateral wall segments. However, in the right panel, a first pass gadolinium enhanced perfusion image also acquired at peak stress is displayed. The yellow arrows indicate a hypoperfused region of the LV myocardium consistent with inducible ischemia. This participant underwent contrast coronary angiography which demonstrated a >70% stenosis of the saphenous vein graft to the right coronary artery.

Mentions: For each LV myocardial segment, a two-step process was utilized to identify perfusion defects indicative of ischemia. First, regions of first-pass hypo-perfusion were measured as a percentage of the corresponding myocardial wall thickness for that LV myocardial segment in the same imaging plane (Figure 1). The radial length of the PD was expressed as a percentage of the total LV myocardial wall thickness. In addition, the duration (or number of frames) for each PD was calculated from onset of LV myocardial enhancement until complete resolution of the defect. Any PD that persisted for more than 5 frames from onset of myocardial enhancement and encompassed >25% of the thickness of the wall was further evaluated for classification as ischemic [15]. This criterion of 25% transmural involvement was used successfully by other investigators to exclude dark rim artifacts [16,17].Figure 1


Mechanism of decreased sensitivity of dobutamine associated left ventricular wall motion analyses for appreciating inducible ischemia in older adults.

Vasu S, Little WC, Morgan TM, Stacey RB, Ntim WO, Hamilton C, Thohan V, Chiles C, Hundley WG - J Cardiovasc Magn Reson (2015)

Discordance between left ventricular wall motion abnormalities and perfusion defects indicative of inducible myocardial ischemia. Cine white blood imaging end-diastolic (left panel) and end-systolic (middle panel) frames from slice position acquired in the middle of the left ventricle at peak dobutamine and atropine infusion administered to achieve >80% of the maximum predicted heart rate response for age. The white arrows indicate normal wall motion of the posterior and lateral wall segments. However, in the right panel, a first pass gadolinium enhanced perfusion image also acquired at peak stress is displayed. The yellow arrows indicate a hypoperfused region of the LV myocardium consistent with inducible ischemia. This participant underwent contrast coronary angiography which demonstrated a >70% stenosis of the saphenous vein graft to the right coronary artery.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4389511&req=5

Fig1: Discordance between left ventricular wall motion abnormalities and perfusion defects indicative of inducible myocardial ischemia. Cine white blood imaging end-diastolic (left panel) and end-systolic (middle panel) frames from slice position acquired in the middle of the left ventricle at peak dobutamine and atropine infusion administered to achieve >80% of the maximum predicted heart rate response for age. The white arrows indicate normal wall motion of the posterior and lateral wall segments. However, in the right panel, a first pass gadolinium enhanced perfusion image also acquired at peak stress is displayed. The yellow arrows indicate a hypoperfused region of the LV myocardium consistent with inducible ischemia. This participant underwent contrast coronary angiography which demonstrated a >70% stenosis of the saphenous vein graft to the right coronary artery.
Mentions: For each LV myocardial segment, a two-step process was utilized to identify perfusion defects indicative of ischemia. First, regions of first-pass hypo-perfusion were measured as a percentage of the corresponding myocardial wall thickness for that LV myocardial segment in the same imaging plane (Figure 1). The radial length of the PD was expressed as a percentage of the total LV myocardial wall thickness. In addition, the duration (or number of frames) for each PD was calculated from onset of LV myocardial enhancement until complete resolution of the defect. Any PD that persisted for more than 5 frames from onset of myocardial enhancement and encompassed >25% of the thickness of the wall was further evaluated for classification as ischemic [15]. This criterion of 25% transmural involvement was used successfully by other investigators to exclude dark rim artifacts [16,17].Figure 1

Bottom Line: Dobutamine associated left ventricular (LV) wall motion analyses exhibit reduced sensitivity for detecting inducible ischemia in individuals with increased LV wall thickness.This study was performed to better understand the mechanism of this reduced sensitivity in the elderly who often manifest increased LV wall thickness and risk factors for coronary artery disease.These findings provide insight as to why dobutamine associated wall motion analyses exhibit reduced sensitivity for identifying inducible ischemia in elderly.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal medicine, Section on Cardiology, Wake Forest School of Medicine, Winston Salem, North Carolina, 27157, USA. svasu@wakehealth.edu.

ABSTRACT

Background: Dobutamine associated left ventricular (LV) wall motion analyses exhibit reduced sensitivity for detecting inducible ischemia in individuals with increased LV wall thickness. This study was performed to better understand the mechanism of this reduced sensitivity in the elderly who often manifest increased LV wall thickness and risk factors for coronary artery disease.

Methods: During dobutamine cardiovascular magnetic resonance (DCMR) stress testing, we assessed rate pressure product (RPP), aortic pulse wave velocity (PWV), LV myocardial oxygen demand (pressure volume area, PVA, mass, volumes, concentricity, and the presence of wall motion abnormalities (WMA) and first pass gadolinium enhanced perfusion defects (PDs) indicative of ischemia in 278 consecutively recruited individuals aged 69 ± 8 years with pre-existing or known risk factors for coronary artery disease. Each variable was assessed independently by personnel blinded to participant identifiers and analyses of other DCMR or hemodynamic variables.

Results: Participants were 80% white, 90% hypertensive, 43% diabetic and 55% men. With dobutamine, 60% of the participants who exhibited PDs had no inducible WMA. Among these participants, myocardial oxygen demand was lower than that observed in those who had both wall motion and perfusion abnormalities suggestive of ischemia (p = 0.03). Relative to those with PDs and inducible WMAs, myocardial oxygen demand remained different in these individuals with PDs without an inducible WMA after accounting for LV afterload and contractility (p = 0.02 and 0.03 respectively), but not after accounting for either LV stress related end diastolic volume index (LV preload) or resting concentricity (p = 0.31-0.71).

Conclusions: During dobutamine stress testing, elderly patients experience increased LV concentricity and declines in LV preload and myocardial oxygen demand, all of which are associated with an absence of inducible LV WMAs indicative of myocardial ischemia. These findings provide insight as to why dobutamine associated wall motion analyses exhibit reduced sensitivity for identifying inducible ischemia in elderly.

Trial registration: This study was registered with Clinicaltrials.gov (NCT00542503).

No MeSH data available.


Related in: MedlinePlus