Dobutamine stress echocardiography predicts left ventricular remodeling after acute myocardial infarction

Prognostic value of divergent pattern detection by 99mTc-sestamibi gated SPECT in patients with anterior acute myocardial infarction

PURPOSE

In gated myocardial perfusion SPECT, apical remodeling may be identified by the presence of a divergent pattern (DP) of the left ventricle (LV).

METHODS AND RESULTS

We examined 150 anterior ST-elevation myocardial infarction (STEMI) patients, all successfully treated with primary percutaneous coronary interventions (PCI). Perfusion gated-SPECT to measure infarct size, LV end-diastolic (ED) and end-systolic (ES) volumes and ejection fraction (EF) was acquired before hospital discharge and repeated at 6-month follow-up. DP was observed in 26 patients, who had larger infarct size (28 ± 19% vs. 15.7 ± 17%, P < 0.02), and lower EF (33 ± 7% vs. 41 ± 10%, P < 0.001) than patients without DP. At follow-up, DP patients had significantly larger EDV (156 ± 54 vs. 107 ± 44 mL, P < 0.0001), ESV (104 ± 47 vs. 59 ± 36 mL, P < 0.0001) and lower EF (35 ± 12% vs. 48 ± 13%, P < 0.0001). 54% of DP patients developed remodeling at follow-up vs. 12% of those without DP (P < 0.001). During follow up, 7 events in the DP group (27%) and 11 events in patients without DP (9%; P < 0.02) occurred. Kaplan-Meier survival curves showed a worse prognosis for DP patients.

CONCLUSION

In patients with anterior AMI, early DP detection is related to subsequent LV dysfunction, larger infarct size, and worse severity. It is helpful for predicting LV remodeling at short-term follow-up and has prognostic implications.

Low-dose dobutamine adds incremental value to late gadolinium enhancement cardiac magnetic resonance in the prediction of adverse remodelling following acute myocardial infarction

AIMS

To examine the relative and combined value of late gadolinium enhancement (LGE) and low-dose dobutamine (LDD) cardiac magnetic resonance (CMR) to predict 'adverse remodelling' (AR) following acute myocardial infarction (AMI).

METHODS AND RESULTS

Forty-five patients with AMI were recruited. CMR was performed 2-4 days after presentation and at 6 months. Ventricular wall motion and volume were recorded at rest and following dobutamine infusion. Measures of first pass perfusion, persistent microvascular obstruction (PMO), and LGE were obtained following contrast administration. Quantitation was performed using the MEDIS 6.2 software. Regression analysis was employed to determine the univariables and multivariate models most predictive of AR at 6 months. The incremental and relative value of LDD over LGE was investigated. The most predictive univariable was 'volume of PMO' (r = 0.51, r2 = 0.26, P < 0.001). The optimal 'combined' multivariate model, utilizing data from all components, was highly predictive of AR (r = 0.82, r2 = 0.67, P < 0.001). The optimal model using parameters only from the LGE component also predicted remodelling (r = 0.65, r2 = 42.0, P = 0.001) but with less accuracy. In contrast, the optimal model using variables from the LDD component alone predicted remodelling with a similar accuracy to the optimal combined model (r = 0.82, r2 = 0.67, P < 0.001).

CONCLUSION

A comprehensive CMR examination accurately predicts AR following AMI. LDD is superior to LGE CMR in this respect. These data suggest that LDD not only adds incremental value to LGE in the prediction of remodelling post-AMI but also may be utilized alone with the same predictive power.

Rest and low-dose dobutamine Tc-99m-mibi gated-SPECT for early prediction of left ventricular remodeling after a first reperfused myocardial infarction

BACKGROUND

Left ventricular (LV) remodeling after myocardial infarction (MI) occurs frequently despite successful percutaneaous coronary intervention (PCI) but cannot be predicted by simple clinical parameters.

METHODS AND RESULTS

This prospective study tested the value of rest and low-dose dobutamine (LDD) Tc-99m-mibi gated-SPECT for early prediction of LV remodeling in patients treated by PCI in the acute phase of a first MI. Infarct size, infarct severity, regional wall motion abnormality (RWMA), and wall thickening score (WTs) were assessed at rest and on LDD by SPECT 6 +/- 2 days after MI in 40 patients. LV remodeling was defined as 20% increase at 6 months in LV end-diastolic volume assessed by MRI. Infarct severity at rest showed the best predictive values for left remodeling (PPV: 86%, NPV: 88%, accuracy: 88%; AUC: 0.750). Functional parameters at neither rest nor LDD study further improved predictive values of the SPECT imaging.

CONCLUSIONS

Infarct severity assessed by Tc-99m-sestamibi gated-SPECT performed in the subacute phase of a first STEMI predicts LV remodeling with high accuracy without incremental value nor of functional parameters nor of LDD. Therefore, our results suggest that LDD should not be used in this setting.

Left ventricular remodeling can be predicted with left ventricular volume response during dobutamine echocardiography after acute myocardial infarction

OBJECTIVES

This study was performed to evaluate the significance of left ventricular (LV) volume response during dobutamine stress echocardiography (DSE) in the prediction of LV volume change during follow-up (F/U) in patients with acute myocardial infarction (AMI).

METHODS

Forty-five patients with AMI (male 39, age 57+/-10 y, anterior myocardial infarction [MI] 29) underwent DSE 6+/-4 d after AMI. Revascularization of the infarct-related artery was performed if severe stenosis was present. A F/U echocardiography was performed 7.5+/-3.4 mo after DSE. The LV end-diastolic volume (EDV) and end-systolic volume (ESV) using the modified Simpson's method were measured at baseline echocardiography, low-dose (10 microg x kg(-1) x min(-1)) DSE, and F/U echocardiography.

RESULTS

Patients were divided into 2 groups; Group I (n = 21) with an abnormal response (<10% decrease) in LVEDV during low-dose DSE; Group II (n = 24) with a normal response (> or =10% decrease) in LVEDV during low-dose DSE. At F/U echocardiography, the (%) change of LVEDV was significantly different between the 2 groups (-2.0+/-16.7 versus - 22.6+/-24.7%, p<0.01). Using multivariate analysis, the response of LVEDV (%) at low-dose DSE was the only significant independent predictor of the change of LVEDV (%) during F/U (y = 0.85 x - 0.03, r = 0.63, p<0.001).

CONCLUSIONS

The response of LVEDV during DSE can be used as a predictor for the LV volume change after AMI.

Evaluation of the left ventricular remodeling in patients with myocardial infarction after revascularization with intravenous real-time myocardial contrast echocardiography

In order to evaluate the left ventricular remodeling in patients with myocardial infarction after revascularization with intravenous real-time myocardial contrast echocardiography (RT-MCE), intravenous RT-MCE was performed on 20 patients with myocardial infarction before coronary revascularization. Follow-up echocardiography was performed 3 months after coronary revascularization. Segmental wall motion was assessed using 18-segment LV model and classified as normal, hypokinesis, akinesis and dyskinesis. Myocardial perfusion was assessed by visual interpretation and divided into 3 conditions: homogeneous opacification=1; partial or reduced opacification or subendocardial contrast defect=2; contrast defect=3. Myocardial perfusion score index (MPSI) was calculated by dividing the total sum of contrast score by the total number of segments with abnormal wall motion. Twenty patients were classified into 2 groups according to the MPSI: MPSI<or=1.5 as good myocardial perfusion, MPSI>1.5 as poor myocardial perfusion. To assess the left ventricular remodeling, the following comparisons were carried out: (1) Comparisons of left ventricular ejection fraction (LVEF), left ventricular end-systolic volume (LVESV) and left ventricular end-diastolic volume (LVEDV) before and 3 months after revascularization in two groups; (2) Comparisons of LVEF, LVESV and LVEDV pre-revascularization between two groups and comparisons of these 3 months post-revascularization between two groups; (3) Comparisons of the differences in LVEF, LVESV and LVEDV between 3 months post-and pre-revascularization (DeltaLVEF, DeltaLVESV and DeltaLVEDV) between two groups; (4) The linear regression analysis between DeltaLVEF, DeltaLVESV, DeltaLVEDV and MPSI. The results showed that the LVEF obtained 3 months after revascularization in patients with MPSI>1.5 was obviously lower than that in those with MPSI<or=1.5. The LVEDV obtained 3 months post-revascularization in patients with MPSI>1.5 was obviously larger than that in those with MPSI<or=1.5 (P=0.002 and 0.04). The differences in DeltaLVEF and DeltaLVEDV between patients with MPSI>1.5 and those with MPSI<or=1.5 were significant (P=0.002 and 0.001, respectively). Linear regression analysis revealed that MPSI had a negative correlation with DeltaLVEF and a positive correlation with DeltaLVESV, DeltaLVEDV (P=0.004, 0.008, and 0.016, respectively). It was concluded that RT-MCE could accurately evaluate the left ventricular remodeling in patients with myocardial infarction after revascularization.

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.

Influence of contractile reserve and inducible ischaemia on left ventricular remodelling after acute myocardial infarction

OBJECTIVE

To assess the relative influence of contractile reserve and inducible ischaemia on subsequent left ventricular volume changes after myocardial infarction.

DESIGN

Left ventricular end diastolic and end systolic index volumes were calculated prospectively at discharge and at six months in 143 patients referred for early postinfarction dobutamine stress echocardiography. On the basis of their responses to this test, patients were divided into three groups: scar (n = 48; group 1); contractile reserve (n = 36; group 2); inducible ischaemia (n = 59; group 3).

RESULTS

At six months, the left ventricular end diastolic index volume decreased in group 2 (mean (SD), -3.9 (9.4) ml/m2) and increased in both group 1 (+2.8 (10.6) ml/m2, p = 0.009 v group 2) and group 3 (+7.5 (11.4) ml/m2, p < 0.0001 v group 2). The end systolic index volume decreased in group 2 (-4.9 (7.3) ml/m2) and increased in both group 1 (+1.3 (8.3) ml/m2, p = 0.0015 v group 2) and group 3 (+2.8 (8.9) ml/m2, p = 0.0002 v group 2). In multivariate analysis, the contractile reserve (hazard ratio 0.19, 95% confidence interval (CI) 0.14 to 0.47), inducible ischaemia (5.86, 95% CI 1.54 to 29.7), and end systolic index volume at discharge (1.04, 95% CI 0.99 to 1.11) were independent predictors of an increase in end diastolic index volume of > or = 15 ml/m2 at six months.

CONCLUSIONS

Contractile reserve and inducible ischaemia, as detected by early dobutamine stress echocardiography, identify patients with differences in long term left ventricular remodelling after acute myocardial infarction.

Relationship between late potentials and myocardial viability assessed by dobutamine echocardiography in the early postinfarction period

BACKGROUND

In the postmyocardial infarction period, late potentials (LPs) are a sensitive marker for the occurrence of sustained ventricular tachycardia and ventricular fibrillation. The relationship between positive signal-averaged electrocardiogram (SAECG) and myocardial viability remains controversial. The aim of the present study was to assess prospectively the possible relationship between LPs and myocardial viability detected by dobutamine stress echocardiography (DSE) in the early period after myocardial infarction (AMI), before hospital discharge.

DESIGN

Ninety-nine patients with AMI were included prospectively in the study. The mean age was 58 +/- 11 years, 17 were women and 82 were men. All patients had SAEG and DSE, and 94 had coronary angiography before hospital discharge.

RESULTS

In the overall population, presence of viability was demonstrated in fewer patients with LPs [37 of 70 (52%)] than absence of viability [18 of 29 (62%)] but the difference did not reach statistical significance. In the subgroup of patients with left ventricular ejection fraction (LVEF) lower than 40%, at higher risk of arrhythmias, the presence of viability was associated with the absence of LPs: 80% of the patients without LPs had viability by DSE (P < 0.01) and only 35% of patients with LPs had viability by DSE (not significant).

CONCLUSIONS

In patients with an acute myocardial infarction and with low ejection fraction (<40%), the absence of LPs is related to the presence of viable myocardium as assessed by DSE early after the acute event. These data also suggest that myocardial viability is not the substrate for LPs in this population.

Myocardial viability: impact on left ventricular dilatation after acute myocardial infarction

OBJECTIVE

To evaluate whether the presence of viable myocardium, detected by low dose dobutamine echocardiography, limits the likelihood of left ventricular dilatation in patients with acute myocardial infarction.

PATIENTS

107 patients were studied by low dose dobutamine echocardiography at (mean (SD)) 3 (1) days after acute myocardial infarction. Cross sectional echocardiography was repeated three months later. Patients were divided in two groups based on the presence (n = 47) or absence (n = 60) of myocardial viability.

RESULTS

Baseline characteristics were comparable between the two groups, except for infarct location. Left ventricular end diastolic volume index (EDVI) was stable in patients with viability, but end systolic volume index (ESVI) decreased significantly (p = 0.006). Patients without viability had a significant increase in both EDVI (p < 0.0001) and ESVI (p = 0.0007). Subgroup analysis in patients with small and large infarcts (peak creatine kinase < or = 1000 v > 1000 IU/l) showed that ventricular dilatation occurred only in patients with large infarcts without viability. This resulted in larger ESVI values at three months in that group compared with patients with large infarcts plus viability (p < 0.05). Multivariate regression analysis identified myocardial viability as an independent predictor of left ventricular dilatation, along with wall motion score index on low dose dobutamine echocardiography and the number of pathological Q waves.

CONCLUSIONS

The presence of viability early after acute myocardial infarction is associated with preservation of left ventricular size, whereas the absence of viability results in ventricular dilatation, particularly in large infarcts.

Relationship between mitral regurgitation and myocardial viability after acute myocardial infarction: their impact on prognosis

Mitral regurgitation (MR) after acute myocardial infarction (AMI) is an important prognostic factor. Although its mechanisms are still debated, ventricular remodeling probably plays an important role. Because myocardial viability (MV) in the infarct zone reduces infarct expansion and ventricular remodeling, it is also possible that its presence counteracts the development of mitral regurgitation in infarcted patients. To evaluate this issue 191 patients with uncomplicated AMI, wall motion abnormalities (akinesis) and semiquantitative evaluation of MR were retrospectively selected from those consecutively examined at our echo-laboratory to evaluate MV using low-dose dobutamine echocardiography (DbE). Follow-up evaluation was performed at 30+/-13 months. Seventy-nine patients had no MR; 86 patients had grade 1 MR, 11 patients had grade 2 MR, nine patients had grade 3 MR, and six patients had grade 4 MR. Patients with significant MR (>grade 1) were older (63+/-7 vs. 59+/-10 years, P=0.03), had lower reduction of RWMSI (DeltaRWMSI) during DbE (0.08+/-0.11 vs. 0.22+/-0.28, P=0.01), more stenotic vessels at coronary angiography (2.35+/-0.93 vs. 1.67+/-1.12, P=0.01), and more frequently had anterior-inferior AMI (P<0.0001); they also had a non-significant tendency to higher RWMSI (2.04+/-0.38 vs. 1.92+/-0.28, P=0.06). In a multivariate regression analysis, DeltaRWMSI proved to be significantly related to the grade of MR (P=0.02). Eighteen patients died during follow-up. Death was more frequent in patients with MR (10/165 vs. 8/26, P=0.0003). At multivariate stepwise Cox regression analysis both the extent of ventricular dysfunction and the presence of MR were significantly related to mortality (P<0.0001 and P=0.01, respectively); DeltaRWMSI showed a non-significant tendency to influence mortality (P=0.09). When MR was excluded from the multivariate analysis, DeltaRWMSI remained significantly related to mortality (P=0.05). In conclusion our study suggests that the presence of MV in infarcted patients influences the development of MR. This reduction of MR may be one of the mechanisms by which MV affects mortality after AMI and should be considered in all studies that evaluate MV after myocardial infarction.