Revascularization in patients with chronic ischaemic myocardial dysfunction: insights from cardiovascular magnetic resonance imaging

Functional Recovery after Intramyocardial Injection of Adipose-Derived Stromal Cells Assessed by Cardiac Magnetic Resonance Imaging

Aims

A major clinical concern is the continuous increase in the number of patients diagnosed with advanced coronary artery disease, ischemic heart failure, and refractory angina, and one of the most promising treatment options for these conditions is stem cell-based therapy. The aim of this study was to assess the functional improvement following intramyocardial injection of adipose-derived stromal cells, using cardiac magnetic resonance.

Methods and Results

Thirteen patients with ischemic heart failure, reduced left ventricular ejection fraction, refractory angina, and who have been disqualified from any form of direct revascularization were enrolled in the study with transthoracic autologous adipose-derived stromal cell implantation. All patients underwent cardiac magnetic resonance prior to the procedure and after 12 months of follow-up. A significant increase in stroke volume (83.1 ± 8.5 mL vs 93.8 ± 13.8 mL, p = 0.025) and stroke volume index (43.3 ± 7.6 mL/m² vs 48.7 ± 9.1 mL/m², p = 0.019), a statistical trend toward an increase in left ventricle ejection fraction (36.7 ± 13.2 vs 39.7 ± 14.9, p = 0.052), and cardiac output improvement (5.0 ± 0.7 vs 5.5 ± 0.9, p = 0.073) was observed in the patient postprocedure. Enhanced relative regional thickening was noted in the segments with adipose-derived stromal cell implantation.

Conclusions

Intramyocardial adipose-derived stromal cell implantation is a promising therapeutic option for selected, symptomatic patients with ischemic heart failure, who have preserved myocardial viability despite being unsuitable for direct revascularization.

Myocardial revascularization in chronic coronary syndromes: does viability matter?

Coronary artery disease (CAD) is the leading cause of death worldwide and improving the prognosis and survival of patients with ischemic heart disease remains a priority of cardiovascular specialists. This article will review the principles of myocardial viability, present the noninvasive imaging tests available to clinicians, as well as critically appraise the latest literature on myocardial viability, coronary revascularization and outcome with a final outlook at studies in the pipelines and future evidence in myocardial viability that will be soon available.

A systematic comparison of cardiovascular magnetic resonance and high resolution histological fibrosis quantification in a chronic porcine infarct model

The noninvasive reference standard for myocardial fibrosis detection on cardiovascular magnetic resonance imaging (CMR) is late gadolinium enhancement (LGE). Currently there is no consensus on the preferred method for LGE quantification. Moreover myocardial wall thickening (WT) and strain are measures of regional deformation and function. The aim of this research was to systematically compare in vivo CMR parameters, such as LGE, WT and strain, with histological fibrosis quantification. Eight weeks after 90 min ischemia/reperfusion of the LAD artery, 16 pigs underwent in vivo Cine and LGE CMR. Histological sections from transverse heart slices were digitally analysed for fibrosis quantification. Mean fibrosis percentage of analysed sections was related to the different CMR techniques (using segmentation or feature tracking software) for each slice using a linear mixed model analysis. The full width at half maximum (FWHM) technique for quantification of LGE yielded the highest R2 of 60%. Cine derived myocardial WT explained 16-36% of the histological myocardial fibrosis. The peak circumferential and radial strain measured by feature tracking could explain 15 and 10% of the variance of myocardial fibrosis, respectively. The used method to systematically compare CMR image data with digital histological images is novel and feasible. Myocardial WT and strain were only modestly related with the amount of fibrosis. The fully automatic FWHM analysis technique is the preferred method to detect myocardial fibrosis.

[Myocardial regional thickness in patients with and without cardiomyopathy assessed by cardiac magnetic resonance]

OBJECTIVE

To explore regional differences in myocardial wall thickness (WT) among the most prevalent cardiomyopathies and in individuals without structural heart disease using cardiac magnetic resonance.

METHODS

Patients older than 18 years referred to cardiac magnetic resonance during the period between January 2014 and September 2014, with a diagnosis of hypertrophic cardiomyopathy, idiopathic dilated cardiomyopathy, ischemic cardiomyopathy, and myocarditis were retrospectively selected from our database.

RESULTS

One hundred twenty patients patients were included. The control group had an average WT of 5.9±1.1mm, with a WT index of 2.9±0.8. Significantly lower mean WT in the apical segments were identified in both the control group (basal 6.7±1.3 vs. mid 6.0±1.3 vs. apical 4.6±1.0mm, P<.0001) and in all evaluated cardiomyopathies (hypertrophic cardiomyopathy: basal 10.5±2.4 vs. mid 10.8±2.7 vs. apical 7.3±3.3mm, P<.0001; idiopathic dilated cardiomyopathy: basal 7.7±1.7 vs. mid 7.6±1.3 vs. apical 5.4±1.3mm, P<.0001; ischemic cardiomyopathy: basal 7.4±1.7 vs. mid 7.5±1.9 vs. apical 5.5±1.8mm, P<.0001; myocarditis: basal 7.1±1.5 vs. mid 6.4±1.1 vs. apical 5.1±0.8, P<.0001). Significant gender differences were also evident regarding the mean WT both in the control group (male 6.5±2.1 vs. female 5.2±1.7mm, P<.0001), as in hypertrophic cardiomyopathy (10.5±5.3 vs. 8.5±5.7mm, P<.0001) and myocarditis (6.6±2.0 vs. 5.2±1.6mm, P<.0001).

CONCLUSION

We found a relatively high prevalence of segments commonly deemed thinned among patients without structural heart disease. We also observed a marked asymmetry and longitudinal gradient in wall thickness both in controls and in the various cardiomyopathies evaluated.

Prediction of long-term segmental and global functional recovery of hibernating myocardium after revascularisation based on low dose dobutamine and late gadolinium enhancement cardiovascular magnetic resonance

BACKGROUND

This study sought to evaluate the relation between long-term segmental and global functional outcome after revascularisation in patients with chronic ischaemic left ventricular dysfunction (LVD) and baseline markers of viability: late gadolinium enhancement (LGE) transmurality and contractile reserve (CR).

METHODS

Forty-two patients with chronic ischaemic LVD underwent low-dose dobutamine- (LDD) and late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) before surgical or percutaneous revascularisation. Regional and global left ventricular (LV) functions and LGE were repeatedly assessed 6 ± 1 and 35 ± 6 months after revascularisation. In total, 319 at baseline dysfunctional and successfully revascularised segments were available for statistical analysis.

RESULTS

The likelihood of long-term functional improvement was directly related to the presence of CR and inversely related to both the LGE and the degree of contractile dysfunction at baseline. The time course of functional improvement was protracted, with significantly more delay in segments with more extensive LGE (p = 0.005) and more severe contractile dysfunction at baseline (p = 0.002). The presence of CR was the predictor of earlier functional improvement (p < 0.0001). Using a definition of viable segment as a segment without any LGE or with any LGE and producing CR during LDD stimulation, ≥ 55% of viable segments from all dysfunctional and revascularised segments in a patient was the only independent predictor of significant improvement (≥ 5%) in the left ventricular ejection fraction (LVEF) after revascularisation, with a 72% sensitivity and an 80% specificity (AUC 0.76, p = 0.014). Reverse LV remodelling was observed in patients who had a significant amount of viable myocardium successfully revascularised.

CONCLUSIONS

In patients with chronic ischaemic LVD, improvement of dysfunctional but viable myocardium can be considerably delayed. Both the likelihood and the time course of functional improvement are related to the LGE, CR and the degree of contractile dysfunction at baseline. At 35 ± 6 months after revascularisation, patients with ≥55% of viable segments from all dysfunctional and revascularised segments significantly improve LVEF and experience reverse LV remodelling. A combination of LDD-CMR and LGE-CMR is a simple and powerful tool for identifying which patients with impaired LV function will benefit from revascularisation.