Changes in transmural distribution of myocardial perfusion assessed by quantitative intravenous myocardial contrast echocardiography in humans

Comparison of myocardial contrast echocardiography with SPECT in the evaluation of coronary artery disease in asymptomatic patients with LBBB

OBJECTIVE

The non-invasive assessment of coronary artery disease (CAD) in patients with left bundle branch block (LBBB) is troublesome. In this study, we investigated the diagnostic accuracy of myocardial contrast echocardiography (MCE) with adenosine to detect CAD in asymptomatic patients with LBBB, and we compared it with single photon emission computed tomography (SPECT) with adenosine.

METHODS

Forty-seven patients with LBBB, and no previously documented CAD, initially underwent SPECT imaging and 1-3 days later MCE. Coronary arteriography was performed within 1 week from the latter procedure.

RESULTS

The overall sensitivity, specificity, positive predictive value, negative predictive value, diagnostic accuracy, and kappa index of concordance of SPECT were 73%, 72%, 44%, 90%, 72%, and 0.37+/-0.13, respectively, whereas those of MCE were 91%, 92%, 77%, 97%, 92%, and 0.77+/-0.1, respectively (p<0.05 for all comparisons). Significant CAD was present in 11 patients (23%). Left anterior descending coronary artery was involved in 8 patients, left circumflex artery in 2 patients, and right coronary artery in 4 patients. Concerning the left anterior descending artery disease detection, SPECT had a sensitivity of 75%, a specificity of 79%, a positive predictive value of 43%, a negative predictive value of 94%, and a diagnostic accuracy of 79%. The respective values of MCE were 100% for all of the above variables.

CONCLUSIONS

MCE with adenosine has a higher global diagnostic accuracy compared to SPECT for the detection of CAD in patients with LBBB, mainly due to the poor specificity of SPECT concerning perfusion defects detection in the left anterior descending artery territory.

Intravenous myocardial contrast echocardiography predicts regional and global left ventricular remodelling after acute myocardial infarction: comparison with low dose dobutamine stress echocardiography

OBJECTIVE

To assess the role of intravenous myocardial contrast echocardiography (MCE) in predicting functional recovery and regional or global left ventricular (LV) remodelling after acute myocardial infarction (AMI) compared with low dose dobutamine stress echocardiography (LDSE).

METHODS

21 patients with anterior AMI and successful primary angioplasty underwent MCE and LDSE during the subacute stage (2-4 weeks after AMI). Myocardial perfusion and contractile reserve were assessed in each segment (12 segment model) with MCE and LDSE. The 118 dyssynergic segments in the subacute stage were classified as recovered, unchanged, or remodelled according to wall motion at six months' follow up. Percentage increase in LV end diastolic volume (%DeltaEDV) was also calculated.

RESULTS

The presence of perfusion was less accurate than the presence of contractile reserve in predicting regional recovery (55% v 81%, p < 0.0001). However, the absence of perfusion was more accurate than the absence of contractile reserve in predicting regional remodelling (83% v 48%, p < 0.0001). The number of segments without perfusion was an independent predictor of %DeltaEDV, whereas the number of segments without contractile reserve was not. The area under the receiver operating characteristic curve showed that the number of segments without perfusion predicted substantial LV dilatation (%DeltaEDV > 20%) more accurately than did the number of segments without contractile reserve (0.88 v 0.72).

CONCLUSION

In successfully revascularised patients with AMI, myocardial perfusion assessed by MCE is predictive of regional and global LV remodelling rather than of functional recovery, whereas contractile reserve assessed by LDSE is predictive of functional recovery rather than of LV remodelling.

Quantifying myocardial perfusion using contrast echocardiography

There is a complex relation between what can be seen using perfusion imaging techniques, and what can be measured.

Evaluation of Transmural Myocardial Perfusion by Ultra-Harmonic Myocardial Contrast Echocardiography in Reperfused Acute Myocardial Infarction

BACKGROUND

The transmural distribution of myocardial perfusion is important for predicting the contractile reverse of an infarcted wall in reperfused acute myocardial infarction (AMI). Evaluating transmural myocardial perfusion by myocardial contrast echocardiography (MCE) could predict the long-term recovery of left ventricular (LV) function.

METHODS AND RESULTS

The study group comprised 20 consecutive patients with a first-episode anterior AMI with total occlusion of the proximal left anterior descending artery, who underwent successful percutaneous coronary intervention within 24 h of onset. MCE was performed on the 15th day after the onset, using ultraharmonic gray-scale imaging with intermittent end-systolic triggering every 4 beats or every 6 beats. Regions of interest were placed over both the endocardial and epicardial region at the mid-septal level. Regional wall motion (RWM) of the infarcted anterior wall and global LV function were assessed by 2-dimensional echocardiography and left ventriculography in both the acute and chronic phase. The transmural distribution of myocardial perfusion by MCE demonstrated a significant relation with RWM score index (r = 0.75, p = 0.0004). Recovery of RWM and LV ejection fraction (LVEF) at 6 months after reperfusion was significantly greater in the group with good perfusion of the epicardium according to MCE than in the poor perfusion group [RWM (SD/cord); -1.23+/-0.91 vs -3.51+/-0.84, p = 0.001, LVEF (%); 63.8+/-10.4 vs 47.0+/-3.4, p = 0.04].

CONCLUSIONS

Assessing the transmural distribution of myocardial perfusion by MCE can predict the long-term recovery of LV function after a reperfused AMI.

Observation of the ischemic cascade in humans using contrast echocardiography during dobutamine stress

Experimental studies have postulated the ischemic cascade and the present study was designed to elucidate whether it can be observed in the clinical setting. Fifty-three patients suspected of having coronary artery disease were studied. Myocardial perfusion abnormalities (MPA) and wall motion abnormalities (WMA) were assessed simultaneously by infusion of Levovist during dobutamine stress echocardiography. Time - intensity data of myocardial opacification were fitted for Y=A (1-e(-)(beta) (t)) from which the rate of increase (beta) of intensity were derived both at rest and during stress. Wall motion was also given a score. Bright opacification was observed in 50 patients: 25 showed significant stenosis (>50%) in the left anterior descending artery (group II) on coronary angiography and 25 did not (group I). Significant differences were found in the beta ratio (stress/rest) between the 2 groups at a low-dose (2.0+/-0.3 vs 1.5+/-0.5, p<0.05) and at a high-dose of dobutamine (2.7+/-1.0 vs 1.1+/-0.5, p<0.001), whereas the wall motion score differed only at a high-dose. Of the 25 patients in group II, MPA preceded WMA in 12, both occurred at the same stage in 12, and neither MPA nor WMA was seen in 1. These data prove the ischemic cascade clinically, using contrast echocardiography, by demonstrating that MPA precede WMA during dobutamine stress in patients with coronary stenosis.