Different contribution of extent of myocardial injury to left ventricular systolic and diastolic function in early reperfused acute myocardial infarction

Determinants and effects of microvascular obstruction on serial change in left ventricular diastolic function after reperfused acute myocardial infarction

Background

Although left ventricular (LV) diastolic dysfunction is more related to functional capacity after acute myocardial infarction (AMI), the determinants of LV diastolic functional change after reperfused AMI remain unknown. This study aimed to investigate the effects of microvascular obstruction (MVO) on mid-term changes in LV diastolic function after reperfused AMI.

Methods

In a cohort of 72 AMI patients who underwent successful revascularization, echocardiography and cardiovascular magnetic resonance imaging were repeated at 9-month intervals. The late gadolinium enhancement (LGE) amount, segmental extracellular volume fraction, global LV, and left atrial (LA) phasic functions, along with mitral inflow and tissue Doppler measurements, were repeated.

Results

Among the included patients, 31 (43%) patients had MVO. During the 9-month interval, LV ejection fraction (EF) and LV global longitudinal strain (GLS) were significantly improved in accordance with a decrease in LGE amount (from 18.2 to 10.3 g, p < 0.001) and LV mass. The deceleration time (DT) of early mitral inflow (188.6 ms-226.3 ms, p < 0.001) and LV elastance index (Ed; 0.133 1/ml-0.127 1/ml, p = 0.049) were significantly improved, but not in conventional diastolic functional indexes. Their improvements occurred in both groups; however, the degree was less prominent in patients with MVO. The degree of decrease in LGE amount and increase in LVEF was significantly correlated with improvement in LV-Ed or LA phasic function, but not with conventional diastolic functional indexes.

Conclusions

In patients with reperfused AMI, DT of early mitral inflow, phasic LA function, and LV-Ed were more sensitive diastolic functional indexes. The degree of their improvement was less prominent in patients with MVO.

Myocardial Contrast Uptake in Relation to Coronary Artery Disease and Prognosis

During left ventricular opacification (LVO), myocardial contrast uptake (MCU) is frequently observed, but its clinical implication is uncertain. We aimed to investigate the diagnostic performance of MCU and its prognostic value in known or suspected coronary artery disease (CAD). Contrast echocardiography was retrospectively analyzed in 457 patients who had previous coronary angiography <12 mo before LVO. MCU was classified into replacement or interstitial patterns. Subendocardial patterns were further inspected. Events were defined as a primary composite of the occurrence of acute coronary syndrome, heart failure hospitalization, sustained ventricular tachycardia and all-cause mortality. MCU had an 87.6% sensitivity, 75.5% specificity, 73.0% positive predictive value and 87.7% negative predictive value in detecting CAD. After a median follow-up of 17.3 mo, 52 events occurred. Replacement, interstitial and subendocardial MCU patterns were associated with events. In conclusion, the presence of MCU was useful in identifying CAD and provided incremental prognostic value for clinical outcomes.

Early Recovery of Left Ventricular Function After Revascularization in Acute Coronary Syndrome

The aim of this study was to assess the accuracy of echocardiographic techniques in detecting the early recovery of left ventricular (LV) function after revascularization in acute coronary syndrome (ACS). In 80 consecutive patients with ACS (age 55.7 ± 9.4 years, 77% male, 15% with CCS Angina III), an echocardiographic examination of left ventricle regional wall motion abnormalities (LV RWMA), peak systolic strain rate (PSSR), peak systolic strain (PSS) and end systolic strain (ESS) was performed before and after percutaneous intervention (PCI). Of the 80 patients, one vessel stenosis (>70%) was present in 53 (66%), two vessel disease in 12 (15%) and multivessel disease in 15 patients (19%). In total, 51% of patients had hypertension, 40% diabetes and 23% dyslipidemia. After PCI, regional PSS, ESS and PSSR of their segments subtended by the culprit vessel improved; left anterior descending-LAD, circumflex-LCx and right coronary-RCA (p<0.05 for all) as well as global S and SR (p < 0.05 for all). In univariate analysis, hypertension (HTN) (β = -0.294 (-0.313-0.047), p = 0.009, smoking β = -0.244 (-0.289-0.015) =0.03, WMA β = -0.317 (-0.284-0.014), p = 0.004 and the number of diseased vessels β = -0.256 (-0.188- 0.054) p=0.03 were predictors of delta global SR. In multivariate analysis, only HTN β = 0.263 (0.005-3.159) and the number of diseased vessels β =0.263 (0.005 - 3.159), p=0.04) predicted delta global SR. In ACS, the echocardiographic regional myocardial deformation is accurate in detecting early recovery of LV myocardial function after culprit lesion revascularization. Also, the findings of this study support the current practice regarding the crucial importance of proximal epicardial vessel PCI treatment on LV function compared to more distal lesions.

MR findings of microvascular perfusion in infarcted and remote myocardium early after successful primary PCI

Objectives

The aim of the study was to evaluate CMR myocardial first-pass perfusion in the injured region as well as the non-infarcted area in ST-elevation myocardial infarction (STEMI) patients few days after successful primary percutaneous coronary intervention (PCI).

Materials and methods

220 patients with first time STEMI successfully treated with PCI (with or without postconditioning) were recruited from the Postconditioning in STEMI study. Contrast enhanced CMR was performed at a 1.5 T scanner 2 (1–5) days after PCI. On myocardial first-pass perfusion imaging signal intensity (SI) was measured in the injured area and in the remote myocardium and maximum contrast enhancement index (MCE) was calculated. MCE = (peak SI after contrast—SI at baseline) / SI at baseline x 100.

Results

There were no significant differences in first-pass perfusion between patients treated with standard PCI and patients treated with additional postconditioning. The injured myocardium showed a significantly lower MCE compared to remote myocardium (94 ± 55 vs. 113 ± 49; p < 0.001). When patients were divided into four quartiles of MCE in the injured myocardium (MCE injured myocardium), patients with low MCE injured myocardium had: significantly lower ejection fraction (EF) than patients with high MCE injured myocardium, larger infarct size and area at risk, smaller myocardial salvage and more frequent occurrence of microvascular obstruction on late gadolinium enhancement. MCE in the remote myocardium revealed that patients with larger infarction also had significantly decreased MCE in the non-infarcted, remote area.

Conclusion

CMR first-pass perfusion can be impaired in both injured and remote myocardium in STEMI patients treated with primary PCI. These findings indicate that CMR first-pass perfusion may be a feasible method to evaluate myocardial injury after STEMI in addition to conventional CMR parameters.

Electrocardiography based prediction of hypertrophy pattern and fibrosis amount in hypertrophic cardiomyopathy: comparative study with cardiac magnetic resonance imaging

Although, cardiac magnetic resonance imaging (CMR) is a gold standard for risk stratification of hypertrophic cardiomyopathy (HCM), is limited in some situations. We sought to evaluate the predictive power of quantitative electrocardiography in assessing hypertrophy pattern and fibrosis in HCM. Eighty-eight patients with HCM were studied. Voltage of R-S-T waves, number of fragmented QRS (fQRS) complexes, and T wave morphology were measured by 12-lead electrocardiography. Sixteen segmental thickness, late gadolinium enhancement (LGE), native T1, extracellular volume fraction (ECV), and T2, left ventricular (LV) mass and %LGE were measured by CMR. Patterns of LV hypertrophy were classified as pure apical, mixed, or asymmetrical septal hypertrophy. Positive and negative predictive values of biphasic T wave for pure apical type were 70.4 and 63.9%, and the predictive values of precordial negative T wave sums [Formula: see text] 12.5 mm were 69.2 and 79.6%. Precordial S waves, especially Cornell voltage index, were significantly correlated to LV mass index and maximal thickness (p [Formula: see text]0.001). The number of fQRS leads was significantly correlated to %LGE, average ECV, and T2 (all p [Formula: see text]0.001). More than one lead with fQRS could predict [Formula: see text]5% of LGE mass with 58% sensitivity and 63% specificity (p = 0.049, area under the curve = 0.627). However, degree of correlation between maximal thickness and precordial S was poor in cases with fQRS more two leads. T wave morphology and precordial S helps discriminate hypertrophy pattern and maximal hypertrophy, however, in cases with more than two leads of concomitant fQRS, CMR defines fibrosis amount and hypertrophy more accurately.

Clinical implications of hypothermic ventricular fibrillation versus beating-heart technique during cardiopulmonary bypass for pulmonary valve replacement in patients with repaired tetralogy of Fallot

OBJECTIVES

This study aimed to compare the effects of hypothermic ventricular fibrillation and beating-heart techniques during cardiopulmonary bypass (CPB) on postoperative outcomes after simple pulmonary valve replacement in patients with repaired tetralogy of Fallot (TOF).

METHODS

We retrospectively reviewed the data of 47 patients with repaired tetralogy of Fallot at a single institution, who received pulmonary valve replacement under the ventricular fibrillation or beating-heart technique without cardioplegic cardiac arrest during CPB between January 2005 and April 2015.

RESULTS

The patients were divided into fibrillation (n = 32) and beating-heart (n = 15) groups. On comparing these groups, the fibrillation group had a larger sinotubular junction (27.1 ± 4.6 vs 22.1 ± 2.4 mm), had a longer operation duration (396 ± 108 vs 345 ± 57 min), required more postoperative transfusions (2.1 ± 2.6 vs 5.0 ± 6.3 units) and had a higher vasoactive-inotropic score at intensive care unit admission (8.0 vs 10, all P < 0.05). Echocardiographic data indicated that the systolic internal diameter of the left ventricle was larger in the fibrillation group than in the beating-heart group immediately after surgery and at the 1-year follow-up. Major adverse cardiac events occurred in 3 cases, all from the fibrillation group. Among 7 patients from the fibrillation group with transoesophageal echocardiography data during CPB, 6 had fully opened aortic valves during fibrillation, causing flooding into the left ventricle and left ventricle distension.

CONCLUSIONS

The postoperative outcomes are worse with the ventricular fibrillation technique than with the beating-heart technique during CPB for pulmonary valve replacement in patients with repaired tetralogy of Fallot.

Two-dimensional longitudinal strains and torsion analysis to assess the protective effects of ischemic postconditioning on myocardial function: a speckle tracking echocardiography study in rabbits

The reperfusion injury that occurs in the early reperfusion often results in myocardial dysfunction. This study evaluated global and regional left ventricular (LV) function using speckle tracking echocardiography (STE) in a rabbit ischemia-reperfusion (I/R) model with and without ischemic postconditioning (I-PostC). The aim is to investigate the potential benefit of I-PostC for myocardial function and validate whether regional longitudinal strain is an appropriate index to indicate myocardial dysfunction. Forty rabbits were divided into an ischemia-reperfusion group (group I) and an I-PostC group (group II). After the coronary arteries were ligated, LV systolic strain and twist parameters decreased, and absolute value of strain rate of isovolumetric relaxation period (SRivr) and post-systolic strain index (PSI) increased significantly in both groups (all p<0.05). After reperfusion, regional longitudinal systolic strain rate (SRsys), systolic strain (Ssys), LV twist and untwisting rate increased, and SRivr and PSI decreased in group II. These changes were not seen in group I. All STE parameters were correlated with area of necrosis (AN)/area at risk (AR) (all p<0.05). The correlations were morerelevant between SRsys and AN/AR (r=-0.673) and between Ssys and AN/AR (r=-0.777) (both p<0.001). The intra- and inter-observer repeatability of STE parameters were good with correlation coefficients (CCs) >0.8 or 0.6. The sensitivities of GSRsys, GSsys, SRsys, Ssys, and LV twist to detect the myocardial infarction were 81.3%, 62.5%, 87.5%, 93.8% and 81.3%, respectively. And the specificities of those parameters were 75.0%, 81.2%, 75.0%, 87.5% and 68.7%. These results indicate that STE is useful for quantitative detection on myocardial function improvement induced by I-PostC in a rabbit I/R model. The regional index-Ssys is an appropriate parameter to indicate myocardial dysfunction because of its sensitivity, specificity, and repeatability.