Abstract
BackgroundEarly recognition of viable myocardium after acute myocardial infarction (AMI) is of clinical relevance, since affected segments have the potential of functional recovery. Delayed contrast-enhanced magnetic resonance imaging (DCE-CMR) has been validated extensively for the detection of viable myocardium. An alternative parameter for detecting viability is the perfusable tissue index (PTI), derived using [15O]H2O positron emission tomography (PET), which is inversely related to the extent of myocardial scar (non-perfusable tissue). The aim of the present study was to investigate the predictive value of PTI on recovery of LV function as compared to DCE-CMR in patients with AMI, after successful percutaneous coronary intervention (PCI). MethodsThirty-eight patients with ST elevation myocardial infarction (STEMI) successfully treated by PCI were prospectively recruited. Subjects were examined 1 week and 3 months (mean follow-up time: 97 ± 10 days) after AMI using [15O]H2O PET and DCE-CMR to assess PTI, regional function and scar. Viability was defined as recovery of systolic wall thickening ≥3.0 mm at follow-up by use of CMR. A total of 588 segments were available for serial analysis. ResultsAt baseline, 180 segments were dysfunctional and exhibited DCE. Seventy-three (41%) of these dysfunctional segments showed full recovery during follow-up (viable), whereas 107 (59%) segments remained dysfunctional (nonviable). Baseline PTI of viable segments was 0.94 ± 0.09 and was significantly higher compared to nonviable segments (0.80 ± 0.13, P < .001). The optimal cut-off value for PTI was ≥0.85 with a sensitivity of 85% and specificity of 72%, and an area under the curve (AUC) of 0.82. In comparison, a cut-off value of <32% for the extent of DCE resulted in a sensitivity of 72% and a specificity of 69%, and an AUC of 0.75 (AUC PTI vs DCE P = .14). ConclusionAssessment of myocardial viability shortly after reperfused AMI is feasible using PET. PET-derived PTI yields a good predictive value for the recovery of LV function in PCI-treated STEMI patients, in excellent agreement with DCE-CMR.
Highlights
After an acute myocardial infarction (AMI), the injured myocardium contains both reversibly damaged (‘viable, or stunned’) and irreversibly damaged (‘nonviable’) tissue, even after successful restoration of coronary reperfusion
The optimal cutoff value for perfusable tissue index (PTI) was ‡0.85 with a sensitivity of 85% and specificity of 72%, and an area under the curve (AUC) of 0.82
The aim of the present study was to investigate the predictive value of PTI on recovery of left ventricular (LV) function after successful primary percutaneous coronary intervention (PCI) for AMI compared against a background of Delayed contrast-enhanced magnetic resonance imaging (DCE-CMR)
Summary
After an acute myocardial infarction (AMI), the injured myocardium contains both reversibly damaged (‘viable, or stunned’) and irreversibly damaged (‘nonviable’) tissue, even after successful restoration of coronary reperfusion. Recognition of dysfunctional but viable myocardium is of clinical relevance, since affected segments have the potential of (complete) functional recovery. Of the various diagnostic techniques available for detecting viability in AMI, delayed contrast-enhanced cardiac magnetic resonance imaging (DCE-CMR) has been evaluated extensively, and it has been shown that the extent of regional hyperenhancement is inversely related to functional improvement after reperfusion.[1,2] More recently, the presence of microvascular injury has been shown to have incremental value over DCE alone in predicting viability.[3] the significance of contrast patterns in AMI remains ambiguous, as other reports have shown differences in contrast wash-out due to ischemia-induced alterations in the pharmacokinetics of gadolinium.[4,5] dysfunctional but viable myocardium may show hyperenhancement, thereby limiting the accuracy of DCE-CMR for delineating viable from necrotic myocardium in the (sub)acute phase of myocardial infarction. Recognition of viable myocardium after acute myocardial infarction (AMI) is of clinical relevance, since affected segments have the potential of functional recovery. The aim of the present study was to investigate the predictive value of PTI on recovery of LV function as compared to DCE-CMR in patients with AMI, after successful percutaneous coronary intervention (PCI)
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