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Stunning and left ventricular function--how long is the ventricle knocked out? Left ventricular function correlated
B A Kaufmann1, M E Pfisterer, S Viswanathan
1Department of Cardiology, University Hospital, Basel, Switzerland. bkaufmann@datacomm.ch
Insights
Myocardial stunning significantly impacts post-stress ejection fraction within one hour of stress testing. Beyond this timeframe, ischemia
Area of Science:
- Cardiology
- Nuclear Cardiology
- Cardiovascular Imaging
Background:
- Myocardial stunning, a transient impairment of cardiac function post-ischemia, is a known phenomenon.
- The relationship between the severity of ischemia and the duration of myocardial stunning remains incompletely understood.
- Accurate assessment of myocardial function post-ischemia is crucial for patient management and prognosis.
Purpose of the Study:
- To investigate the impact of ischemic severity on myocardial stunning.
- To determine the duration of myocardial stunning following ischemic events.
- To characterize the relationship between ischemia extent and post-stress ejection fraction.
Main Methods:
- 310 patients underwent myocardial perfusion SPECT (MPS) using a rest Thallium/stress Technetium-99m sestamibi protocol.
- Myocardium ischemic percentage was quantified, and post-stress ejection fraction (psEF) was assessed using QGS.
- Patients were grouped by ischemia extent and imaging time (< or = 60 min vs. > 60 min post-stress).
Main Results:
- Patients with ischemia had significantly lower psEF compared to those with normal MPS (56+/-8% vs. 61+/-8%, p=0.006).
- Greater ischemia extent (>10% myocardium) correlated with lower psEF (49+/-9% vs. 53+/-11%, p=0.006).
- Within 60 minutes post-stress, higher ischemia severity significantly reduced psEF (p=0.037); this effect diminished after 60 minutes (p=0.12).
Conclusions:
- Ischemia significantly impacts post-stress ejection fraction (psEF) when imaging occurs within one hour of stress.
- Myocardial stunning's relevance in interpreting psEF appears diminished beyond one hour post-stress.
- The timing of imaging after stress is critical for assessing the functional impact of ischemia.
Purpose:
Little is known about the relation between severity of ischemia and duration of myocardial stunning. The aim of this study was therefore to characterize the impact of ischemia on myocardial stunning and on its duration.
Methods:
310 patients (pts) who underwent myocardial perfusion SPECT (MPS) were evaluated. MPS acquired with a rest Thallium/stress Technetium-99m sestamibi protocol were scored with respect to % myocardium ischemic. Left ventricular post-stress ejection fraction (psEF) was evaluated by the widely used QGS algorithm. Resting LVEF (rEF) was assessed by invasive ventriculography. Patient groups were then compared with respect to different extents of ischemia and different time intervals between stress and imaging (< or = 60 min and > 60 min after stress).
Results:
21% of pts had a normal MPS, 8% had evidence of scar, 37% had evidence of ischemia, and 34% had evidence of scar plus ischemia. Pts with normal MPS had a significantly higher psEF than pts with ischemia, 61+/-8% and 56+/-8%, respectively (p=0.006), whereas rEF was not different. Overall, pts with < or = 10% myocardium ischemic had significantly higher psEF than pts with > 10% myocardium ischemic, 53+/-11% and 49+/-9%, respectively (p=0.006), whereas rEF was not different. In pts with evidence of ischemia who underwent imaging < or = 60 min after stress testing, pts with < or = 10% myocardium ischemic had higher psEF than pts with > 10% myocardium ischemic, 60+/-7% and 53+/-8%, respectively (p=0.037). In contrast, pts with evidence of ischemia who underwent imaging > 60 min after stress testing had similar psEF irrespective of extent of ischemia (53%+/-8 in pts with < or = 10% ischemia and 54%+/-8 in pts with > 10% myocardium ischemic, p=0.12).
Conclusions:
Ischemia had a significant impact on psEF in patients who underwent imaging less than 1 h after stress. More than one hour after stress testing stunning seems to be less relevant in the interpretation of psEF.
