Assessment of myocardial fibrosis by endoventricular electromechanical mapping in experimental nonischemic cardiomyopathy

Iron accumulation and lipid peroxidation: implication of ferroptosis in diabetic cardiomyopathy

Diabetic cardiomyopathy (DC) is a serious heart disease caused by diabetes. It is unrelated to hypertension and coronary artery disease and can lead to heart insufficiency, heart failure and even death. Currently, the pathogenesis of DC is unclear, and clinical intervention is mainly symptomatic therapy and lacks effective intervention objectives. Iron overdose mediated cell death, also known as ferroptosis, is widely present in the physiological and pathological processes of diabetes and DC. Iron is a key trace element in the human body, regulating the metabolism of glucose and lipids, oxidative stress and inflammation, and other biological processes. Excessive iron accumulation can lead to the imbalance of the antioxidant system in DC and activate and aggravate pathological processes such as excessive autophagy and mitochondrial dysfunction, resulting in a chain reaction and accelerating myocardial and microvascular damage. In-depth understanding of the regulating mechanisms of iron metabolism and ferroptosis in cardiovascular vessels can help improve DC management. Therefore, in this review, we summarize the relationship between ferroptosis and the pathogenesis of DC, as well as potential intervention targets, and discuss and analyze the limitations and future development prospects of these targets.

Contact-force monitoring increases accuracy of right ventricular voltage mapping avoiding “false scar” detection in patients with no evidence of structural heart disease

Purpose

Electroanatomical mapping (EAM) could increase cardiac magnetic resonance imaging (CMR) sensitivity in detecting ventricular scar. Possible bias may be scar over-estimation due to inadequate tissue contact. Aim of the study is to evaluate contact-force monitoring influence during EAM, in patients with idiopathic right ventricular arrhythmias.

Methods

20 pts (13 M; 43 ± 12 y) with idiopathic right ventricular outflow tract (RVOT) arrhythmias and no structural abnormalities were submitted to Smarttouch catheter Carto3 EAM. Native maps included points collected without considering contact-force. EAM scar was defined as area ≥1 cm² including at least 3 adjacent points with signal amplitude (bipolar <0.5 mV, unipolar 3,5 mV), surrounded by low-voltage border zone. EAM were re-evaluated offline, removing points collected with contact force <5 g. Finally, contact force-corrected maps were compared to the native ones.

Results

An EAM was created for each patient (345 ± 85 points). After removing poor contact points, a mean of 149 ± 60 points was collected. The percentage of false scar, collected during contact force blinded mapping compared to total volume, was 6.0 ± 5.2% for bipolar scar and 7.1 ± 5.9% for unipolar scar, respectively. No EAM scar was present after poor contact points removal. Right ventricular areas analysis revealed a greater number of points with contact force < 5 g acquired in free wall, where reduced mean bipolar and unipolar voltage were recorded.

Conclusions

To date this is the first work conducted on structurally normal hearts in which contact-force significantly increases EAM accuracy, avoiding “false scar” related to non-adequate contact between catheter and tissue.

Paeonol Reverses Adriamycin Induced Cardiac Pathological Remodeling through Notch1 Signaling Reactivation in H9c2 Cells and Adult Zebrafish Heart

Adriamycin is a commonly prescribed chemotherapeutic drug for a wide range of cancers. Adriamycin causes cardiotoxicity as an adverse effect that limits its clinical application in cancer treatment. Several mechanisms have been proposed to explain the toxicity it causes in heart cells. Disruption of inherent cardiac repair mechanism is the least understood mechanism of Adriamycin-induced cardiotoxicity. Adriamycin induces pathological remodeling in cardiac cells by promoting apoptosis, hypertrophy, and fibrosis. We found that Adriamycin inhibited Notch1 in a time- and dose-dependent manner in H9c2 cells. We used Paeonol, a Notch1 activator, and analyzed the markers of apoptosis, hypertrophy, and fibrosis in H9c2 cells in vitro and in adult zebrafish heart in vivo as model systems to study Adriamycin-induced cardiotoxicity. Paeonol activated Notch1 signaling and expression of its downstream target genes effectively in the Adriamycin-treated condition in vitro and in vivo. Also we detected that Notch activation using Paeonol protected the cells from apoptosis, collagen deposition, and hypertrophy response using functional assays. We conclude that Adriamycin induced cardiotoxicity by promoting the pathological cardiac remodeling through inhibition of Notch1 signaling and that the Notch1 reactivation by Paeonol protected the cells and reversed the cardiotoxicity.

CD34+ Cell Transplantation Improves Right Ventricular Function in Patients with Nonischemic Dilated Cardiomyopathy

We investigated the effects of CD34⁺ cell therapy on right ventricular (RV) function in patients with nonischemic dilated cardiomyopathy (DCM). We enrolled 60 patients with DCM who were randomized to CD34⁺ cell therapy (Stem Cells (SC) Group n = 30), or no cell therapy (Controls, n = 30). The SC Group received granulocyte‐colony stimulating factor, and CD34⁺ cells were collected by apheresis and injected transendocardially. Patients were followed for 6 months. At baseline, the groups did not differ in age, gender, left ventricular ejection fraction, N‐terminal probrain natriuretic peptide, or parameters of RV function. At 6 months, we found a significant improvement in RV function in the SC Group (tricuspid annular plane systolic excursion [TAPSE]: +0.44 ± 0.64 cm, p = .001; peak systolic tissue Doppler velocity of tricuspid annulus [St]: +1.5 ± 2.1 cm/s; p = .001; percent of fractional area change [FAC]: +8.6% ± 5%, p = .01), but not in Controls (TAPSE: −0.07 ± 0.32 cm, p = .40; St: −0.1 ± 1.2 cm/s; p = .44; FAC: −1.2% ± 3.2%, p = .50). On repeat electroanatomical mapping, we found an improvement in interventricular septum viability in 19 of 30 patients from the SC Group; this correlated with the improvements in RV function (13/19 in the improved septum group versus 3/11 in the remaining cohort, p = .029). These results suggest that patients with DCM, changes in RV function correlate with changes of viability of interventricular septum. CD34⁺ cell therapy appears to be associated with improved right ventricular function in this patient cohort. (Clinical Trial Registration Information: www.clinicaltrials.gov; NCT02248532). Stem Cells Translational Medicine2018;7:168–172

Three-dimensional myocardial scar characterization from the endocardium: Usefulness of endocardial unipolar electroanatomic mapping

Epicardial ablation may be required to eliminate ventricular tachycardia (VT) in patients with underlying structural heart disease. The decision to gain epicardial access is frequently based on the suspicion of an epicardial origin for the VT and/or presence of an arrhythmogenic substrate. Epicardial pathology and VT is frequently present in patients with nonischemic right and/or left cardiomyopathies even in the setting of modest or no endocardial bipolar voltage substrate. In this setting, unipolar voltage mapping from the endocardium serves to help identify midmyocardial and/or epicardial VT substrate. The additional value of endocardial unipolar mapping includes its usefulness to predict the clinical outcome after VT ablation, to determine the irreversibility of myocardial disease, and to guide endomyocardial biopsy procedures to specific areas of intramural scarring. In this review, we aim to provide a guide to the use of endocardial unipolar mapping and its appropriate interpretation in a variety of clinical situations.

A Review on the Effect of Traditional Chinese Medicine Against Anthracycline-Induced Cardiac Toxicity

Anthracyclines are effective agents generally used to treat solid-tumor and hematologic malignancies. The use of anthracyclines for over 40 years has improved cancer survival statistics. Nevertheless, the clinical utility of anthracyclines is limited by its dose-dependent cardiotoxicity that adversely affects 10-30% of patients. Anthracycline-induced cardiotoxicity may be classified as acute/subacute or chronic/late toxicity and leads to devastating adverse effects resulting in poor quality of life, morbidity, and premature mortality. Traditional Chinese medicine has a history of over 2,000 years, involving both unique theories and substantial experience. Several studies have investigated the potential of natural products to decrease the cardiotoxic effects of chemotherapeutic agents on healthy cells, without negatively affecting their antineoplastic activity. This article discusses the mechanism of anthracycline-induced cardiotoxicity, and summarizes traditional Chinese medicine treatment for anthracycline-induced heart failure (HF), cardiac arrhythmia, cardiomyopathy, and myocardial ischemia in recent years, in order to provide a reference for the clinical prevention and treatment of cardiac toxicity.

Cellular Therapy for Heart Failure

The pathogenesis of cardiomyopathy and heart failure (HF) is underpinned by complex changes at subcellular, cellular and extracellular levels in the ventricular myocardium. For all of the gains that conventional treatments for HF have brought to mortality and morbidity, they do not adequately address the loss of cardiomyocyte numbers in the remodeling ventricle. Originally conceived to address this problem, cellular transplantation for HF has already gone through several stages of evolution over the past two decades. Various cell types and delivery routes have been implemented to positive effect in preclinical models of ischemic and nonischemic cardiomyopathy, with pleiotropic benefits observed in terms of myocardial remodeling, systolic and diastolic performance, perfusion, fibrosis, inflammation, metabolism and electrophysiology. To a large extent, these salubrious effects are now attributed to the indirect, paracrine capacity of transplanted stem cells to facilitate endogenous cardiac repair processes. Promising results have also followed in early phase human studies, although these have been relatively modest and somewhat inconsistent. This review details the preclinical and clinical evidence currently available regarding the use of pluripotent stem cells and adult-derived progenitor cells for cardiomyopathy and HF. It outlines the important lessons that have been learned to this point in time, and balances the promise of this exciting field against the key challenges and questions that still need to be addressed at all levels of research, to ensure that cell therapy realizes its full potential by adding to the armamentarium of HF management.

Protective effect of Sheng-Mai Yin, a traditional Chinese preparation, against doxorubicin-induced cardiac toxicity in rats

Background

Sheng-Mai Yin (SMY), a modern Chinese formula based on Traditional Chinese Medicine theory, has been used to treat cardiovascular diseases in Eastern Asia. Our study focuses on the cardioprotection of SMY against doxorubicin (DOX)-induced cardiac toxicity in vivo.

Methods

Rats were injected with DOX (2.5 mg/kg) in six injections over a 2-week period. SMY was administrated intragastrically at the dose of 8.35, 16.7 and 33.4 g/kg, or 16.7 g/kg only twice a day concurrently with DOX for the 2-weeks. A series of assays were performed to detect the effects of SMY on: (i) heart weight index (HWI) and left ventricular mass index (LVMI); (ii) cardiac function; (iii) heart tissue morphology; (iv) the contents of carboxy terminal propeptide of procollagen typeI (PICP), amino terminal propeptide of procollagen type III (PШNP), transforming growth factor-β1 (TGF-β1), B-type natriuretic peptide (BNP), monocyte chemoattractant protein-1 (MCP-1), interferon gamma (INF-γ) and interleukin 6 (IL-6) by ELISA; (v) the mRNA levels of TGF-β1 and toll-like receptor-2 (TLR2); and (vi) protein level of TGF-β1.

Results

Rats treated with SMY displayed the reductions of BNP and CK-MB increased by DOX in a dose-dependent manner. Moderate dose of SMY exhibited the correction for the increased HWI, LVMI, and the injured cardiac function, as well as the collagen accumulation. In addition, cardioprotection of SMY against DOX-induced cardiac toxicity was demonstrated by the reduction of myocardial fibrosis, characterized by the suppression of PICP, PШNP and TGF-β1, as well as the anti-inflammation and the regulation for cardiac immune microenvironment, characterized by the inhibition of TLR2, MCP-1, INF-γ and IL-6.

Conclusions

SMY may protect heart function through the restriction of myocardial fibrosis induced by DOX, which suggests the potentially therapeutic effect of SMY on DOX-induced cardiomyopathy.

Continuing treatment with Salvia miltiorrhiza injection attenuates myocardial fibrosis in chronic iron-overloaded mice

Iron overload cardiomyopathy results from iron accumulation in the myocardium that is closely linked to iron-mediated myocardial fibrosis. Salvia miltiorrhiza (SM, also known as Danshen), a traditional Chinese medicinal herb, has been widely used for hundreds of years to treat cardiovascular diseases. Here, we investigated the effect and potential mechanism of SM on myocardial fibrosis induced by chronic iron overload (CIO) in mice. Kunming male mice (8 weeks old) were randomized to six groups of 10 animals each: control (CONT), CIO, low-dose SM (L-SM), high-dose SM (H-SM), verapamil (VRP) and deferoxamine (DFO) groups. Normal saline was injected in the CONT group. Mice in the other five groups were treated with iron dextran at 50 mg/kg per day intraperitoneally for 7 weeks, and those in the latter four groups also received corresponding daily treatments, including 3 g/kg or 6 g/kg of SM, 100 mg/kg of VRP, or 100 mg/kg of DFO. The iron deposition was estimated histologically using Prussian blue staining. Myocardial fibrosis was determined by Masson's trichrome staining and hydroxyproline (Hyp) quantitative assay. Superoxide dismutase (SOD) activity, malondialdehyde (MDA) content and protein expression levels of type I collagen (COL I), type I collagen (COL III), transforming growth factor-β1 (TGF-β1) and matrix metalloproteinase-9 (MMP-9) were analyzed to investigate the mechanisms underlying the effects of SM against iron-overloaded fibrosis. Treatment of chronic iron-overloaded mice with SM dose-dependently reduced iron deposition levels, fibrotic area percentage, Hyp content, expression levels of COL I and COL III, as well as upregulated the expression of TGF- β1 and MMP-9 proteins in the heart. Moreover, SM treatment decreased MDA content and increased SOD activity. In conclusion, SM exerted activities against cardiac fibrosis induced by CIO, which may be attributed to its inhibition of iron deposition, as well as collagen metabolism and oxidative stress.

New insight into scar-related ventricular tachycardia circuits in ischemic cardiomyopathy: Fat deposition after myocardial infarction on computed tomography--A pilot study

BACKGROUND

Myocardial fat deposition (FAT-DEP) has been frequently observed in regions of chronic myocardial infarction in patients with ischemic cardiomyopathy. The role of FAT-DEP within scar-related ventricular tachycardia (VT) circuits has not been investigated.

OBJECTIVE

This pilot study aimed to assess the impact of myocardial FAT-DEP on local electrograms and VT circuits in patients with ischemic cardiomyopathy.

METHODS

Contrast-enhanced computed tomography was performed in 22 patients with ischemic VT. Electroanatomic map points were registered to the corresponding contrast-enhanced computed tomography images. Myocardial FAT-DEP was identified and characterized using a postprocessing image overlay that highlighted areas below 0 Hounsfield units (HU). The mean attenuation of local myocardial regions corresponding to sampled electrograms was measured on short-axis images. The associations of mean attenuation with bipolar and unipolar amplitudes, left ventricular wall thickness, and VT circuit sites were investigated.

RESULTS

Of 1801 electroanatomic map points, 519 (28.8%) were located in regions with FAT-DEP. Significant differences were observed in mean intensity (23.2 ± 35.6 HU vs 81.7 ± 21.9 HU; P < .001), bipolar (0.75 ± 0.83 mV vs 2.9 ± 2.4 mV; P < .001) and unipolar (3.1 ± 1.7 mV vs 7.4 ± 4.3 mV; P < .001) amplitudes, and left ventricular wall thickness (5.2 ± 1.7 mm vs 8.2 ± 2.5 mm; P < .001) between regions with and without FAT-DEP. Lower HU was strongly associated with lower bipolar and unipolar amplitudes (P < .0001, respectively). Importantly, FAT-DEP was associated with critical VT circuit sites with fractionated or isolated potentials.

CONCLUSION

FAT-DEP was associated with electrogram characteristics and VT circuit sites. Further work will be needed to determine whether FAT-DEP plays a causal role in the generation of ischemic scar-related VT circuits.

The presence of electromechanical mismatch in nonischemic dilated cardiomyopathy is associated with ventricular repolarization instability

BACKGROUND

We analyzed electromechanical mismatch (EMM) and its relationship to ventricular repolarization in patients with nonischemic dilated cardiomyopathy (DCM).

METHODS AND RESULTS

In 39 DCM patients with left ventricular ejection fraction (LVEF) <40% and New York Heart Association functional class ≥III, electroanatomic mapping was used to quantify areas of EMM. High-resolution electrocardiograph was used to measure heart rate variability (HRV) and QT variability index (QTVI). EMM was present in 22 patients (56%, group 1), whereas 17 patients presented no mismatched segments (44%, group 2). The groups did not differ in age (56 ± 10 years in group 1 vs 57 ± 7 years in group 2; P = .82), sex (male: 82% vs 94%; P = .40), LVEF (27 ± 8% vs 25 ± 6%; P = .18), or N-terminal pro-B-type natriuretic peptide (2,350 pg/mL vs 2,831 pg/mL; P = .32). Although heart rate and HRV were similar in both groups (rate: 80 ± 20 beats/min in group 1 vs 74 ± 19 beats/min in group 2 [P = .47]; standard deviation of normal-to normal RR intervals: 106 ± 79 vs 88 ± 115 [P = .61]), we found significantly higher QTVI values in patients from group 1 (-1.15 ± 0.46 vs -1.62 ± 0.51 in group 2; P = .005). In patients with implantable cardioverter-defibrillators, ventricular arrhythmias recorded ≤1 year before enrollment were more frequent in group 1 than in group 2 (58% vs 13%; P = .02).

CONCLUSIONS

EMM is present in a majority of patients with DCM and is associated with ventricular repolarization instability.

Notch-1 mediated cardiac protection following embryonic and induced pluripotent stem cell transplantation in doxorubicin-induced heart failure

Doxorubicin (DOX), an effective chemotherapeutic drug used in the treatment of various cancers, is limited in its clinical applications due to cardiotoxicity. Recent studies suggest that transplanted adult stem cells inhibit DOX-induced cardiotoxicity. However, the effects of transplanted embryonic stem (ES) and induced pluripotent stem (iPS) cells are completely unknown in DOX-induced left ventricular dysfunction following myocardial infarction (MI). In brief, C57BL/6 mice were divided into five groups: Sham, DOX-MI, DOX-MI+cell culture (CC) media, DOX-MI+ES cells, and DOX-MI+iPS cells. Mice were injected with cumulative dose of 12 mg/kg of DOX and 2 weeks later, MI was induced by coronary artery ligation. Following ligation, 5×10⁴ ES or iPS cells were delivered into the peri-infarct region. At day 14 post-MI, echocardiography was performed, mice were sacrificed, and hearts were harvested for further analyses. Our data reveal apoptosis was significantly inhibited in ES and iPS cell transplanted hearts compared with respective controls (DOX-MI+ES: 0.48±0.06% and DOX-MI+iPS: 0.33±0.05% vs. DOX-MI: 1.04±0.07% and DOX-MI+CC: 0.96±0.21%; p<0.05). Furthermore, a significant increase in levels of Notch-1 (p<0.05), Hes1 (p<0.05), and pAkt (p<0.05) were observed whereas a decrease in the levels of PTEN (p<0.05), a negative regulator of Akt, was evident following stem cell transplantation. Moreover, hearts transplanted with stem cells demonstrated decreased vascular and interstitial fibrosis (p<0.05) as well as MMP-9 expression (p<0.01) compared with controls. Additionally, heart function was significantly improved (p<0.05) in both cell-transplanted groups. In conclusion, our data show that transplantation of ES and iPS cells blunt DOX-induced adverse cardiac remodeling, which is associated with improved cardiac function, and these effects are mediated by the Notch pathway.

Akt-mTOR Pathway Inhibits Apoptosis and Fibrosis in Doxorubicin-Induced Cardiotoxicity Following Embryonic Stem Cell Transplantation

Doxorubicin (DOX) is an effective chemotherapeutic drug used for the treatment of a variety of malignancies. Unfortunately, time and dose-dependent DOX therapy induces cardiotoxicity and heart failure. We previously reported that transplanted embryonic stem (ES) cells and the conditioned medium (CM) can repair and regenerate injured myocardium in acute DOX-induced cardiomyopathy (DIC). However, the effectiveness of ES cell and CM therapeutics has not been challenged in the chronic DIC model. To this end, the long-term impact of ES cells and CM on apoptosis, fibrosis, cytoplasmic vacuolization, oxidative stress, and their associated mediators were examined. Four weeks post-DIC, ES cells and CM-transplanted hearts showed a significant decrease in cardiac apoptotic nuclei, which was consequent to modulation of signaling molecules in the Akt pathway including PTEN, Akt, and mTOR. Cytoplasmic vacuolization was reduced following treatment with ES cells and CM, as was cardiac fibrosis, which was attributable to downregulation of MMP-9 activity. Oxidative stress, as evidenced by DHE staining and lipid peroxide concentration, was significantly diminished, and preservation of the antioxidant defense system was observed following CM and ES cell transplantation. In conclusion, our data suggest that transplanted ES cells and CM have long-term potentiation to significantly mitigate various adverse pathological mechanisms present in the injured chronic DIC heart.

Embryonic Stem Cells and Released Factors Stimulate c-kit(+)/FLK-1(+) Progenitor Cells and Promote Neovascularization in Doxorubicin-Induced Cardiomyopathy

Vascular apoptosis plays a pivotal role in the development and progression of a myriad of cardiac dysfunctions, but has yet to be investigated in doxorubicin-induced cardiomyopathy (DIC). Additionally, the neovascularization potential and resulting functional consequences of embryonic stem (ES) cells and factors released from these cells in the chronic DIC myocardium remain largely unknown. To this end, we transplanted conditioned media (CM) and ES cells in the DIC-injured heart and evaluated their potential to inhibit vascular cell death, activate endogenous c-kit(+) and FLK-1(+) cells, enhance neovascularization, and augment left ventricular dysfunction. Data presented suggest transplanted CM and ES cells significantly blunt vascular cell apoptosis consequent to DIC. Quantitative immunohistochemistry data demonstrate significantly increased c-kit(+) and FLK-1(+) cells, as well as enhanced differentiated CD31(+) cells in the CM and ES cell groups relative to DIC controls. Heart function, including fractional shortening and ejection fraction, assessed by transthoracic echocardiography, was significantly improved following CM and ES cell transplantation. In conclusion, our data suggest that transplantation of CM and ES cells inhibit vascular apoptosis, activate endogenous c-kit(+) and FLK-1(+) cells and differentiate them into endothelial cells, enhance neovascularization, and improve cardiac function in the DIC-injured myocardium.

Comparison of transendocardial and intracoronary CD34+ cell transplantation in patients with nonischemic dilated cardiomyopathy

BACKGROUND

In an open-label blinded study, we compared intracoronary and transendocardial CD34(+) cell transplantation in patients with nonischemic dilated cardiomyopathy.

METHODS AND RESULTS

Of the 40 patients with dilated cardiomyopathy, 20 were randomized to receive intracoronary injection and 20 received transendocardial CD34(+) cell delivery. In both groups, CD34(+) cells were mobilized by filgrastim, collected via apheresis, and labeled with technetium-99m radioisotope for single-photon emission computed tomographic imaging. In the intracoronary group, cells were injected intracoronarily in the artery supplying segments of greater perfusion defect on myocardial perfusion scintigraphy. In the transendocardial group, electroanatomic mapping was used to identify viable but dysfunctional myocardium, and transendocardial cell injections were performed. Nuclear single-photon emission computed tomographic imaging for quantification of myocardial retention was performed 18 hours thereafter. At baseline, groups did not differ in age, sex, left ventricular ejection fraction, or N-terminal pro-brain natriuretic peptide levels. The number of CD34(+) cells was also comparable (105 ± 31 × 10(6) in the transendocardial group versus 103 ± 27 × 10(6) in the intracoronary group, P=0.62). At 18 hours after procedure, myocardial retention was higher in the transendocardial group (19.2 ± 4.8%) than in the intracoronary group (4.4 ± 1.2%, P<0.01). At 6 months, left ventricular ejection fraction improved more in the transendocardial group (+8.1 ± 4.3%) than in the intracoronary group (+4.2 ± 2.3%, P=0.03). The same pattern was observed for the 6-minute walk test distance (+125 ± 33 m in the transendocardial group versus +86 ± 13 m in the intracoronary group, P=0.03) and N-terminal pro-brain natriuretic peptide (-628 ± 211 versus -315 ± 133 pg/mL, P=0.04).

CONCLUSIONS

In patients with dilated cardiomyopathy, transendocardial CD34(+) cell transplantation is associated with higher myocardial retention rates and greater improvement in ventricular function, N-terminal pro-brain natriuretic peptide, and exercise capacity compared with intracoronary route.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT01350310.

Impact of nonischemic scar features on local ventricular electrograms and scar-related ventricular tachycardia circuits in patients with nonischemic cardiomyopathy

BACKGROUND

The association of local electrogram features with scar morphology and distribution in nonischemic cardiomyopathy has not been investigated. We aimed to quantify the association of scar on late gadolinium-enhanced cardiac magnetic resonance with local electrograms and ventricular tachycardia circuit sites in patients with nonischemic cardiomyopathy.

METHODS AND RESULTS

Fifteen patients with nonischemic cardiomyopathy underwent late gadolinium-enhanced cardiac magnetic resonance before ventricular tachycardia ablation. The transmural extent and intramural types (endocardial, midwall, epicardial, patchy, transmural) of scar were measured in late gadolinium-enhanced cardiac magnetic resonance short-axis planes. Electroanatomic map points were registered to late gadolinium-enhanced cardiac magnetic resonance images. Myocardial wall thickness, scar transmurality, and intramural scar types were independently associated with electrogram amplitude, duration, and deflections in linear mixed-effects multivariable models, clustered by patient. Fractionated and isolated potentials were more likely to be observed in regions with higher scar transmurality (P<0.0001 by ANOVA) and in regions with patchy scar (versus endocardial, midwall, epicardial scar; P<0.05 by ANOVA). Most ventricular tachycardia circuit sites were located in scar with >25% scar transmurality.

CONCLUSIONS

Electrogram features are associated with scar morphology and distribution in patients with nonischemic cardiomyopathy. Previous knowledge of electrogram image associations may optimize procedural strategies including the decision to obtain epicardial access.

Evaluation of experimental myocardial infarction models via electromechanical mapping and magnetic resonance imaging

The diagnostic characteristics of electromechanical mapping (EMM) were evaluated in porcine myocardial infarction (MI) models with the parallel application of cardiac magnetic resonance imaging (cMRI) from the aspect of different pathophysiology and localization. Balloon occlusion in the left anterior descending coronary artery (LAD balloon group) or coil deployment in the LAD (LAD coil group) or circumflex artery (Cx coil group) was applied percutaneously in 16 domestic pigs. Regional left ventricular viability data were captured via cMRI and EMM. The unipolar voltage (UV) value was significantly decreased in segments containing transmural and subendocardial late enhancement compared with viable segments in the LAD balloon, LAD coil, and Cx coil groups. Receiver operating characteristic analysis revealed area under the curve values of 0.809 and 0.691 in the LAD infarct territory, and 0.864 and 0.855 in the Cx infarct territory for the UV compared with cMRI viability results as transmural late enhancement or viable tissue and subendocardial late enhancement or viable tissue, respectively. In conclusion, the UV value detected the presence of scar tissue with differential transmural extent and which represented proper diagnostic features both in the reperfused and nonreperfused models. This data could provide additional benefit in the clinical use of EMM for diagnostic purposes.

CD34+ stem cell therapy in nonischemic dilated cardiomyopathy patients

Recent trends indicate that patients with nonischemic dilated cardiomyopathy represent the largest subpopulation of heart failure patients with a significant need for alternative treatment modalities. Similar to patients with ischemic cardiomyopathy, patients with nonischemic dilated cardiomyopathy have been found to have myocardial regions with flow abnormalities, which may represent targets for neoangiogenic therapies. CD34(+) stem cells might contribute to the formation of new blood vessels from existing vascular structures in ischemic tissues by the direct incorporation of injected cells into the newly developing vasculature or by the production and secretion of angiogenic cytokines. This review summarizes the long-term clinical effects and potential underlying mechanisms of CD34(+) cell therapy in patients with nonischemic dilated cardiomyopathy.

Myocardial structural associations with local electrograms: a study of postinfarct ventricular tachycardia pathophysiology and magnetic resonance-based noninvasive mapping

BACKGROUND

The association of scar on late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) with local electrograms on electroanatomic mapping has been investigated. We aimed to quantify these associations to gain insights regarding LGE-CMR image characteristics of tissues and critical sites that support postinfarct ventricular tachycardia (VT).

METHODS AND RESULTS

LGE-CMR was performed in 23 patients with ischemic cardiomyopathy before VT ablation. Left ventricular wall thickness and postinfarct scar thickness were measured in each of 20 sectors per LGE-CMR short-axis plane. Electroanatomic mapping points were retrospectively registered to the corresponding LGE-CMR images. Multivariable regression analysis, clustered by patient, revealed significant associations among left ventricular wall thickness, postinfarct scar thickness, and intramural scar location on LGE-CMR, and local endocardial electrogram bipolar/unipolar voltage, duration, and deflections on electroanatomic mapping. Anteroposterior and septal/lateral scar localization was also associated with bipolar and unipolar voltage. Antiarrhythmic drug use was associated with electrogram duration. Critical sites of postinfarct VT were associated with >25% scar transmurality, and slow conduction sites with >40 ms stimulus-QRS time were associated with >75% scar transmurality.

CONCLUSIONS

Critical sites for maintenance of postinfarct VT are confined to areas with >25% scar transmurality. Our data provide insights into the structural substrates for delayed conduction and VT and may reduce procedural time devoted to substrate mapping, overcome limitations of invasive mapping because of sampling density, and enhance magnetic resonance-based ablation by feature extraction from complex images.

New unipolar electrogram criteria to identify irreversibility of nonischemic left ventricular cardiomyopathy

OBJECTIVES

This study sought to assess the value of left ventricular (LV) endocardial unipolar electroanatomical mapping (EAM) in identifying irreversibility of LV systolic dysfunction in patients with left ventricular nonischemic cardiomyopathy (LVCM).

BACKGROUND

Identifying irreversibility of LVCM would be helpful but cannot be reliably accomplished by bipolar EAM or cardiac magnetic resonance identification of macroscopic scar.

METHODS

Detailed endocardial LV EAM was performed in 3 groups: 1) 24 patients with irreversible LVCM (I-LVCM) but with no or minimal macroscopic scar (<15% LV surface) evidenced on bipolar voltage EAM and/or cardiac magnetic resonance; 2) 14 patients with reversible ventricular premature depolarization-mediated LVCM (R-LVCM); and 3) 17 patients with structurally normal hearts. LV endocardial unipolar electrogram amplitude and area of unipolar amplitude abnormality were defined after excluding macroscopic scar.

RESULTS

Unipolar amplitude differed in the 3 groups: median of 7.6 (interquartile range [IQR]: 5.5 to 9.7) mV in I-LVCM group, 13.2 (IQR: 10.4 to 16.2) mV in R-LVCM group, and 16.3 (IQR: 13.6 to 19.8) mV in structurally normal hearts group (p < 0.001). Areas of unipolar abnormality represented a large proportion of total LV surface in I-LVCM, 64.7% (IQR: 47.5% to 75.9%) compared with R-LVCM, 5.2% (IQR: 0.0% to 19.1%) and structurally normal hearts, 0.1% (IQR: 0.0% to 0.9%), groups (p < 0.001). A unipolar abnormality area cutoff of 32% of total LV surface was 96% sensitive and 100% specific in identifying irreversible cardiomyopathy among patients with LV dysfunction (I-LVCM and R-LVCM), p < 0.001.

CONCLUSIONS

Detailed unipolar voltage mapping can identify irreversible myocardial dysfunction consistent with fibrosis, even in the absence of bipolar EAM or cardiac magnetic resonance abnormalities, and may serve as valuable prognostic tool in patients presenting with LVCM to facilitate clinical decision making.

Dietary omega-3 supplementation exacerbates left ventricular dysfunction in an ovine model of anthracycline-induced cardiotoxicity

BACKGROUND

Cumulative dose-dependent nonischemic cardiomyopathy (NICM) remains a significant risk with the use of some chemotherapeutic agents. In this context, omega-3 polyunsaturated fatty acids (PUFA) have been investigated for their cardioprotective potential in rodent and in vitro models of anthracycline toxicity, with conflicting results. This study evaluated prophylactic omega-3 PUFA supplementation in a large-animal model of anthracycline-induced NICM.

METHODS AND RESULTS

Merino sheep were randomized to oral drenching with omega-3 PUFA (fish oil; n = 8) or olive oil placebo (n = 9) 3 weeks before commencing repeated intracoronary infusions of doxorubicin (DOX) to induce cardiac dysfunction. Cumulative DOX dose was 3.6 mg/kg. Drenching was continued for 12 weeks after final DOX exposure. Despite significant increases in tissue omega-3 PUFA levels (P < .05 vs placebo), omega-3-treated sheep displayed greater signs of anthracycline cardiotoxicity than placebo animals, consisting of left ventricular dilatation and a greater decline in ejection fraction (P < .05), although myocardial fibrosis burden was similar in both groups.

CONCLUSIONS

Dietary intake of omega-3 PUFA fails to prevent and may indeed exacerbate DOX-induced cardiotoxicity. Clinical use of omega-3 supplementation during chemotherapy should be deferred until more information is available regarding the mechanisms of interaction between fatty acids and the myocardium during anthracycline exposure.

Emerging roles for integrated imaging modalities in cardiovascular cell-based therapeutics: a clinical perspective

Despite preclinical promise, the progress of cell-based therapy to clinical cardiovascular practice has been slowed by several challenges and uncertainties that have been highlighted by the conflicting results of human trials. Most telling has been the revelation that current strategies fall short of achieving sufficient retention and engraftment of cells to meet the ambitious objective of myocardial regeneration. This has sparked novel research into the refinement of cell biology and delivery to overcome these shortcomings. Within this context, molecular imaging has emerged as a valuable tool for providing noninvasive surveillance of cell fate in vivo. Direct and indirect labelling of cells can be coupled with clinically relevant imaging modalities, such as radionuclide single photon emission computed tomography and positron emission tomography, and magnetic resonance imaging, to assess their short- and long-term distributions, along with their viability, proliferation and functional interaction with the host myocardium. This review details the strengths and limitations of the different cell labelling and imaging techniques and their potential application to the clinical realm. We also consider the broader, multifaceted utility of imaging throughout the cell therapy process, providing a discussion of its considerable value during cell delivery and its importance during the evaluation of cardiac outcomes in clinical studies.