Real-time assessment of myocardial perfusion during balloon angioplasty of the left anterior descending coronary artery

Real-time perfusion adenosine stress echocardiography versus myocardial perfusion adenosine scintigraphy for the detection of myocardial ischaemia in patients with stable coronary artery disease

BACKGROUND

Real-time perfusion (RTP) contrast echocardiography using low mechanical index power modulation technique allows for simultaneous myocardial perfusion and wall motion analysis. RTP-adenosine stress echocardiography (ASE) could be an alternative to dobutamine-atropine stress echocardiography; more tolerable for the patients and possibly similarly accurate. We aimed to evaluate RTP-ASE for the detection of myocardial ischaemia, compared to 99mTc-sestamibi single-photon emission computed tomography (SPECT).

METHODS

Patients with suspected coronary artery disease, admitted to SPECT evaluation, were prospectively invited to participate. Patients underwent RTP imaging (SONOS 5500) using infusion of Sonovue (Bracco, Milano, Italy) before and during ASE. Two separate readers performed off-line analysis of myocardial perfusion and wall motion by RTP-ASE. A perfusion defect was the principal marker of ischaemia. Wall motion assessment was used to evaluate ischaemia in segments with perfusion artefacts. Each segment was attributed to one of the three main coronary vessel areas of interest: the left anterior descending (LAD); the left circumflex (LCx) and the right posterior descending (RPD). Normal SPECT at stress was judged normal at rest.

RESULTS

In 33 patients, 99 coronary territories were analysed by SPECT and RTP-ASE. SPECT showed evidence of ischaemia in 9 of 33 patients. For the detection of ischaemia, the overall level of agreement between RTP-ASE and SPECT was 92% in all segments. The level of agreement was 88% in LAD, 97% in LCx and 91% in RPD segments.

CONCLUSION

Real-time perfusion-adenosine stress echocardiography using power modulation could be an accurate and feasible tool for evaluation of ischaemia in patients with suspected coronary artery disease. The results from this study need confirmation by a study of a larger patient sample.

Usefulness of real-time myocardial perfusion imaging to evaluate alterations of myocardial blood flow in patients with stable angina pectoris undergoing elective percutaneous coronary interventions

Release of cardiac enzymes has been reported in patients with stable angina who undergo elective percutaneous coronary intervention (PCI) and has been associated with adverse clinical outcomes. The aim of the present study was to investigate whether impaired microvascular integrity can be detected using myocardial contrast echocardiography in patients undergoing elective PCI, and whether it is related to the extent of postprocedural troponin T elevation. We investigated consecutive patients with stable angina (n = 19) who were scheduled for elective angioplasty with stent placement. Myocardial contrast echocardiography was performed before and 2 to 4 hours and 24 hours after coronary intervention. Contrast images were analyzed visually and quantitatively measuring the peak signal intensity (A) and the slope of the signal intensity rise (beta) in 16 myocardial segments. The product of A x beta was calculated in each segment to estimate the regional myocardial blood flow. Troponin T was collected serially before and 2 to 4 hours and 24 hours after PCI. Five patients (26%) had elevated troponin T 24 hours after PCI (range 0.03 to 0.46 microg/L). Eight patients (42%), including all 5 patients with elevated troponin T levels, demonstrated impaired microvascular integrity 2 to 4 hours after PCI in >or=2 myocardial segments (range 2 to 4) within the perfusion territory of the target vessel. Of the 11 patients without evidence of impaired myocardial perfusion by myocardial contrast echocardiography, none had elevated troponin T levels at follow-up. Quantitative analysis of myocardial blood flow showed that impaired perfusion after PCI was partially reversible. Thus, A x beta had decreased significantly at 2 to 4 hours after PCI (3.4 +/- 1.6 vs 8.8 +/- 3.4 dB/s baseline, p <0.01), reincreased after 24 hours (6.4 +/- 2.3 dB/s at 24 hours vs 3.4 +/- 1.6 dB/s at 2 to 4 hours, p <0.01), but did not return to baseline (8.8 +/- 3.4 dB/s at baseline vs 6.4 +/- 2.3 dB/s at 24 hours, p <0.01). The perfusion defect size 2 to 4 hours after PCI was closely related to the troponin T levels after 24 hours (r(2) = 0.80, p <0.0001). In conclusion, impaired microvascular integrity is partially present in patients with stable angina who undergo elective PCI, is partially reversible, and is closely related to the release of troponin T. Because judgment of interventional success has shifted downstream to tissue level perfusion, myocardial contrast echocardiography may be useful to monitor such alterations in myocardial tissue perfusion.

Comparison of dobutamine stress echocardiography with and without real-time perfusion imaging for detection of coronary artery disease

In a pilot study of 27 patients, those who presented with chest pain underwent 2 dobutamine stress echocardiographic studies, 1 with high mechanical index harmonic imaging to analyze wall motion without contrast and 1 with real-time low mechanical index perfusion imaging with intravenous Optison to assess myocardial perfusion and wall motion. All patients then underwent quantitative coronary angiography. Two independent reviewers demonstrated an improvement in sensitivity when analyzing myocardial perfusion. In the 21 patients who had significant coronary stenoses, 14 had abnormal myocardial perfusion detected at peak stress and 7 had abnormal wall motion detected by standard dobutamine stress echocardiography. There was decreased specificity with perfusion imaging by 1 reviewer. The addition of real-time perfusion imaging after intravenous contrast during dobutamine stress echocardiography has the potential to improve detection of coronary artery disease.

Reperfusion assessment using myocardial contrast echocardiography in patients with ST-segment elevation acute myocardial infarction

In this study, 29 patients underwent myocardial contrast echocardiography after presentation with ST-segment elevation acute myocardial infarction but before coronary angiography using a continuous infusion of microbubbles and real-time imaging with a low mechanical index. Patients with transmural perfusion defects at presentation subsequently had much larger infarctions (as measured by peak creatine phosphokinase-MB fraction) than did those with normal perfusion, indicating that myocardial contrast echocardiography may be a useful means to determine adequacy of reperfusion after thrombolytic therapy and in the selection of patients for adjunctive treatment, such as "rescue angioplasty."