Association between acute myocardial infarction-to-cardiac rupture time and in-hospital mortality risk: a retrospective analysis of multicenter registry data from the Cardiovascular Research Consortium-8 Universities (CIRC-8U).

Despite the known association of cardiac rupture with acute myocardial infarction (AMI), it is still unclear whether the clinical characteristics are associated with the risk of in-hospital mortality in patients with AMI complicated by cardiac rupture. The purpose of this study was to investigate the association between the time of cardiac rupture occurrence and the risk of in-hospital mortality after AMI. We conducted a retrospective analysis of multicenter registry data from eight medical universities in Eastern Japan. From 10,278 consecutive patients with AMI, we included 183 patients who had cardiac rupture after AMI, and examined the incidence of in-hospital deaths during a median follow-up of 26 days. Patients were stratified into three groups according to the AMI-to-cardiac rupture time, namely the > 24-h group (n = 111), 24-48-h group (n = 20), and < 48-h group (n = 52). Cox proportional hazards regression analysis was used to estimate the hazard ratio (HR) and the confidence interval (CI) for in-hospital mortality. Around 87 (48%) patients experienced in-hospital death and 126 (67%) underwent a cardiac surgery. Multivariable Cox regression analysis revealed a non-linear association across the three groups for mortality (HR [CI]; < 24 h: 1.0, reference; 24-48 h: 0.73 [0.27-1.86]; > 48 h: 2.25 [1.22-4.15]) after adjustments for age, sex, Killip classification, percutaneous coronary intervention, blood pressure, creatinine, peak creatine kinase myocardial band fraction, left ventricular ejection fraction, and type of rupture. Cardiac surgery was independently associated with a reduction in the HR of mortality (HR [CI]: 0.27 [0.12-0.61]) and attenuated the association between the three AMI-to-cardiac rupture time categories and mortality (statistically non-significant) in the Cox model. These data suggest that the AMI-to-cardiac rupture time contributes significantly to the risk of in-hospital mortality; however, rapid diagnosis and prompt surgical interventions are crucial for improving outcomes in patients with cardiac rupture after AMI.

A multicenter study on the clinical characteristics and risk factors of in-hospital mortality in patients with mechanical complications following acute myocardial infarction.

Mechanical complications (MCs) following acute myocardial infarction (AMI), such as ventricular septal rupture (VSR), free-wall rupture (FWR), and papillary muscle rupture (PMR), are fatal. However, the risk factors of in-hospital mortality among patients with MCs have not been previously reported in Japan. The purpose of this study was to evaluate the prognostic factors of in-hospital mortality in these patients. The study cohort consisted of 233 consecutive patients with MCs from the registry of 10 facilities in the Cardiovascular Research Consortium-8 Universities (CIRC-8U) in East Japan between 1997 and 2014 (2.3% of 10,278 AMI patients). The authors conducted a retrospective observational study to analyse the correlation between the subtypes of MCs with in-hospital mortality, clinical data, and medical treatment. We observed a decreasing incidence of MC (1997-2004: 3.7%, 2005-2010: 2.1%, 2011-2014: 1.9%, p < 0.001). In-hospital mortality among patients with MCs was 46%. Thirty-three percent of patients with MCs were not able to undergo surgical repair due to advanced age or severe cardiogenic shock. In-hospital mortality among patients who had undergone surgical repair was 29% (VSR: 21%, FWR: 33%, PMR: 60%). In patients with MCs, hazard ratio for in-hospital mortality according to multivariate analysis of without surgical repair was 5.63 (95% CI 3.54-8.95). In patients with surgical repair, the hazard ratios of blow-out-type FWR (5.53, 95% confidence interval (CI) 2.22-13.76), those with renal dysfunction (3.11, 95% CI 1.37-7.05), and those receiving venoarterial extracorporeal membrane oxygenation (VA-ECMO) (3.79, 95% CI 1.81-7.96) were significantly high. Although primary percutaneous coronary intervention (PCI) is associated with decreased incidence of MCs, high in-hospital mortality persisted in patients with MCs that also presented with renal dysfunction and in those requiring VA-ECMO. Early detection and surgical repair of MCs are essential.

CD8+ T-cells negatively regulate inflammation post-myocardial infarction.

The adaptive immune response is key for cardiac wound healing post-myocardial infarction (MI) despite low T-cell numbers. We hypothesized that CD8+ T-cells regulate the inflammatory response, leading to decreased survival and cardiac function post-MI. We performed permanent occlusion of the left anterior descending coronary artery on C57BL/6J and CD8atm1mak mice (deficient in functional CD8+ T-cells). CD8atm1mak mice had increased survival at 7 days post-MI compared with that of the wild-type (WT) and improved cardiac physiology at day 7 post-MI. Despite having less mortality, 100% of the CD8atm1mak group died because of cardiac rupture compared with only 33% of the WT. Picrosirius red staining and collagen immunoblotting indicated an acceleration of fibrosis in the infarct area as well as remote area in the CD8atm1mak mice; however, this increase was due to elevated soluble collagen implicating poor scar formation. Plasma and tissue inflammation were exacerbated as indicated by higher levels of Cxcl1, Ccl11, matrix metalloproteinase (MMP)-2, and MMP-9. Immunohistochemistry and flow cytometry indicated that the CD8atm1mak group had augmented numbers of neutrophils and macrophages at post-MI day 3 and increased mast cell markers at post-MI day 7. Cleavage of tyrosine-protein kinase MER was increased in the CD8atm1mak mice, resulting in delayed removal of necrotic tissue. In conclusion, despite having improved cardiac physiology and overall survival, CD8atm1mak mice had increased innate inflammation and poor scar formation, leading to higher incidence of cardiac rupture. Our data suggest that the role of CD8+ T-cells in post-MI recovery may be both beneficial and detrimental to cardiac remodeling and is mediated via a cell-specific mechanism.NEW & NOTEWORTHY We identified new mechanisms implicating CD8+ T-cells as regulators of the post-myocardial infarction (MI) wound healing process. Mice without functional CD8+ T-cells had improved cardiac physiology and less mortality 7 days post MI compared with wild-type animals. Despite having better overall survival, animals lacking functional CD8+ T-cells had delayed removal of necrotic tissue, leading to poor scar formation and increased cardiac rupture, suggesting that CD8+ T-cells play a dual role in the cardiac remodeling process.

Treatment strategies for post-infarction left ventricular free-wall rupture.

Left ventricular free-wall rupture is one of the most fatal complications after acute myocardial infarction. Surgical treatment of post-infarction left ventricular free-wall rupture has evolved over time. Direct closure of the ventricular wall defect (linear closure) and resection of the infarcted myocardium (infarctectomy), with subsequent closure of the created defect with a prosthetic patch, represented the original techniques. Recently, less aggressive approaches, either with the use of surgical glues or the application of collagen sponge patches on the infarct area to cover the tear and achieve haemostasis, have been proposed. Despite such modifications in the therapeutic strategy and surgical treatment, however, postoperative in-hospital mortality may be as high as 35%. In extremely high-risk or inoperable patients, a non-surgical approach has been reported.

Interleukin-35 Promotes Macrophage Survival and Improves Wound Healing After Myocardial Infarction in Mice.

RATIONALE: Targeting inflammation has been shown to provide clinical benefit in the field of cardiovascular diseases. Although manipulating regulatory T-cell function is an important goal of immunotherapy, the molecules that mediate their suppressive activity remain largely unknown. IL (interleukin)-35, an immunosuppressive cytokine mainly produced by regulatory T cells, is a novel member of the IL-12 family and is composed of an EBI3 (Epstein-Barr virus-induced gene 3) subunit and a p35 subunit. However, the role of IL-35 in infarct healing remains elusive. OBJECTIVE: This study aimed to determine whether IL-35 signaling is involved in healing and cardiac remodeling after myocardial infarction (MI) and, if so, to elucidate the underlying molecular mechanisms. METHODS AND RESULTS: IL-35 subunits (EBI3 and p35), which are mainly expressed in regulatory T cells, were upregulated in mice after MI. After IL-35 inhibition, mice showed impaired infarct healing and aggravated cardiac remodeling, as demonstrated by a significant increase in mortality because of cardiac rupture, decreased wall thickness, and worse cardiac function compared with wild-type MI mice. IL-35 inhibition also led to decreased expression of α-SMA (α-smooth muscle actin) and collagen I/III in the hearts of mice after MI. Pharmacological inhibition of IL-35 suppressed the accumulation of Ly6Clow and major histocompatibility complex IIlow/C-C motif chemokine receptor type 2- (MHC IIlow CCR2-) macrophages in infarcted hearts. IL-35 activated transcription of CX3CR1 (C-X3-C motif chemokine receptor 1) and TGF (transforming growth factor) ß1 in macrophages by inducing GP130 signaling, via IL12Rß2 and phosphorylation of STAT1 (signal transducer and activator of transcription family) and STAT4 and subsequently promoted Ly6Clow macrophage survival and extracellular matrix deposition. Moreover, compared with control MI mice, IL-35-treated MI mice showed increased expression of α-SMA and collagen within scars, correlating with decreased left ventricular rupture rates. CONCLUSIONS: IL-35 reduces cardiac rupture, improves wound healing, and attenuates cardiac remodeling after MI by promoting reparative CX3CR1+Ly6Clow macrophage survival.

Sutureless repair for postinfarction left ventricular free wall rupture.

OBJECTIVE: Left ventricular free wall rupture is a catastrophic complication of acute myocardial infarction. Sutureless repair has been reported to be an effective surgical procedure for left ventricular free wall rupture. However, the outcomes of sutureless repair remain unclear. METHODS: Between January 2001 and December 2016, 42 patients were treated for left ventricular free wall rupture at Jichi Medical University. Of them, 35 consecutive patients undergoing sutureless repair using the TachoComb (CSL Behring, Tokyo, Japan) or TachoSil (Nycomed, Zurich, Switzerland) patches were included in this study. No patient required cardiopulmonary bypass. The oozing type of left ventricular free wall rupture was observed in 33 patients (94%), and the blow-out type was observed in 2 patients (6%). The rupture sites were the anterior wall in 16 patients (46%), the posterior-lateral wall in 11 patients (31%), and the inferior wall in 8 patients (23%). RESULTS: The in-hospital mortality rate was 17% (6 patients). Re-rupture after sutureless repair occurred in 17% (6 patients). Of them, 4 cases (67%) of re-rupture occurred within 24 hours after surgery. The 2 patients with blow-out type left ventricular free wall rupture experienced re-rupture. Three patients required mitral valve surgery after sutureless repair during the admission. The overall survivals at 1, 5, and 10 years were 71.4%, 68.6%, and 62.9%, respectively. Multivariable analysis revealed that re-rupture was an independent predictor for decreased survival (hazard ratio, 58.6; 95% confidence interval, 4.9-701.6; P = .001). Postoperative pseudoaneurysm formation was not detected during the follow-up. CONCLUSIONS: Sutureless repair using TachoComb/TachoSil patches can be a viable treatment option for left ventricular free wall rupture. Care should be taken when applying this technique in cases of the blow-out type left ventricular free wall rupture.

Cardiomyocyte-specific deficiency of HSPB1 worsens cardiac dysfunction by activating NFκB-mediated leucocyte recruitment after myocardial infarction.

Aims: Inadequate healing after myocardial infarction (MI) leads to heart failure and fatal ventricular rupture, while optimal healing requires timely induction and resolution of inflammation. This study tested the hypothesis that heat shock protein B1 (HSPB1), which limits myocardial inflammation during endotoxemia, modulates wound healing after MI. Methods and results: To test this hypothesis, cardiomyocyte-specific HSPB1 knockout (Hspb1-/-) mice were generated using the Cre-LoxP recombination system. MI was induced by ligation of the left anterior descending coronary artery in Hspb1-/- and wild-type (WT) littermates. HSPB1 was up-regulated in cardiomyocytes of WT animals in response to MI, and deficiency of cardiomyocyte HSPB1 increased MI-induced cardiac rupture and mortality within 21 days after MI. Serial echocardiography showed more aggravated remodelling and cardiac dysfunction in Hspb1-/- mice than in WT mice at 1, 3, and 7 days after MI. Decreased collagen deposition and angiogenesis, as well as increased MMP2 and MMP9 activity, were also observed in Hspb1-/- mice compared with WT controls after MI, using immunofluorescence, polarized light microscopy, and zymographic analyses. Notably, Hspb1-/- hearts exhibited enhanced and prolonged leucocyte infiltration, enhanced expression of inflammatory cytokines, and enhanced TLR4/MyD88/NFκB activation compared with WT controls after MI. In-depth molecular analyses in both mice and primary cardiomyocytes demonstrated that cardiomyocyte-specific knockout of HSPB1 increased nuclear factor-κB (NFκB) activation, which promoted the expression of proinflammatory mediators. This led to increased leucocyte recruitment, thereby to excessive inflammation, ultimately resulting in adverse remodelling, cardiac dysfunction, and cardiac rupture following MI. Conclusion: These data suggest that HSPB1 acts as a negative regulator of NFκB-mediated leucocyte recruitment and the subsequent inflammation in cardiomyocytes. Cardiomyocyte HSPB1 is required for wound healing after MI and could be a target for myocardial repair in MI patients.

Trimetazidine suppresses oxidative stress, inhibits MMP-2 and MMP-9 expression, and prevents cardiac rupture in mice with myocardial infarction.

BACKGROUND/AIMS: Cardiac rupture (CR) is a catastrophic complication of acute myocardial infarction (MI). At present, there are no effective pharmacological strategies for preventing post-MI rupture. Here we investigated the effect of trimetazidine (TMZ) on post-MI CR. METHODS: MI models were induced by left coronary artery ligation in male C57BL/6 mice. Animals allocated to the rupture incidence were closely monitored for 7 days; autopsy was performed once animals were found dead to determine the reason of death. Heart function was detected by echocardiography. Oxidative stress markers and matrix metalloproteinases (MMPs) were analyzed by Western Blotting. RESULTS: TMZ markedly reduced the post-MI CR incidence of mice. We found that the expression of metalloproteinase (MMP) -2 and MMP-9 in the TMZ-treated group was significantly lower than the saline-treated group. Further, TMZ markedly attenuated MI-induced oxidative stress. To investigate the mechanism of the effect of TMZ on CR, we pretreated H9c2 cells with H2 O2 and found that TMZ treatment markedly decreased H2 O2 -induced MMP-2 and MMP-9 expression. TMZ prevents CR through inhibition of oxidative stress, which is attributable to the down-regulation of MMP-2, MMP-9 expression. CONCLUSIONS: Our findings indicate that TMZ suppresses oxidative stress, inhibits MMP-2 and MMP-9 expression, and prevents CR in mice with MI.

Association of the SYNTAX Score II with cardiac rupture in patients with ST-segment elevation myocardial infarction undergoing a primary percutaneous coronary intervention.

BACKGROUND: Despite advances in reperfusion strategies, medical therapy, and emergent surgery, cardiac rupture (CR) is still a major lethal complication. Numerous parameters have been found to be associated with CR development after a primary percutaneous coronary intervention (pPCI). SYNTAX Score (SS) and SYNTAX Score II (SSII) have been studied in ST-segment elevation myocardial infarction (STEMI) patients, and higher scores have been associated with higher mortality. However, the relationship between CR and SSII is unclear. This study investigates the possible relationship between CR and SS, SSII in STEMI patients treated with pPCI. PATIENTS AND METHODS: We enrolled 1663 consecutive STEMI patients treated with pPCI, who were divided into two groups according to CR development and compared with each other. Patients were further stratified into the three groups according to their SSII values. RESULTS: In this study, 33 (1.98%) patients developed CR. Both SS and SSII of those with CR were significantly higher than those without (19.27±4.0 vs. 16.40±4.55; P<0.001 and 49.40±16.54 vs. 30.92±11.80; P<0.001, respectively). It was also observed that CR increased gradually according to increasing SSII tertiles. SSII was found to be an independent predictor for CR (odds ratio=1.043, 95% confidence interval: 1.012-1.074; P=0.006). In the long-term follow-up, all-cause mortality was significantly higher in patients with CR than those without (60.6 vs. 8.8%; P<0.001). CONCLUSION: This study shows that SSII is an independent predictor for CR. Furthermore, patients with CR were associated with a poor prognosis. Closer follow-up of patients with high SSII may be useful in the early detection and treatment of this fatal complication.

Splenic Ly6Chi monocytes contribute to adverse late post-ischemic left ventricular remodeling in heme oxygenase-1 deficient mice.

Heme oxygenase-1 (Hmox1) is a stress-inducible protein crucial in heme catabolism. The end products of its enzymatic activity possess anti-oxidative, anti-apoptotic and anti-inflammatory properties. Cardioprotective effects of Hmox1 were demonstrated in experimental models of myocardial infarction (MI). Nevertheless, its importance in timely resolution of post-ischemic inflammation remains incompletely understood. The aim of this study was to determine the role of Hmox1 in the monocyte/macrophage-mediated cardiac remodeling in a mouse model of MI. Hmox1 knockout (Hmox1-/-) and wild-type (WT, Hmox1+/+) mice were subjected to a permanent ligation of the left anterior descending coronary artery. Significantly lower incidence of left ventricle (LV) free wall rupture was noted between 3rd and 5th day after MI in Hmox1-/- mice resulting in their better overall survival. Then, starting from 7th until 21st day post-MI a more potent deterioration of LV function was observed in Hmox1-/- than in the surviving Hmox1+/+ mice. This was accompanied by higher numbers of Ly6Chi monocytes in peripheral blood, as well as higher expression of monocyte chemoattractant protein-1 and adhesion molecules in the hearts of MI-operated Hmox1-/- mice. Consequently, a greater post-MI monocyte-derived myocardial macrophage infiltration was noted in Hmox1-deficient individuals. Splenectomy decreased the numbers of circulating inflammatory Ly6Chi monocytes in blood, reduced the numbers of proinflammatory cardiac macrophages and significantly improved the post-MI LV function in Hmox1-/- mice. In conclusion, Hmox1 deficiency has divergent consequences in MI. On the one hand, it improves early post-MI survival by decreasing the occurrence of cardiac rupture. Afterwards, however, the hearts of Hmox1-deficient mice undergo adverse late LV remodeling due to overactive and prolonged post-ischemic inflammatory response. We identified spleen as an important source of these cardiovascular complications in Hmox1-/- mice.

Topiramate modulates post-infarction inflammation primarily by targeting monocytes or macrophages.

AIMS: Monocytes/macrophages response plays a key role in post-infarction inflammation that contributes greatly to post-infarction ventricular remodelling and cardiac rupture. Therapeutic targeting of the GABAA receptor, which is enriched in monocytes/macrophages but not expressed in the myocardium, may be possible after myocardial infarction (MI). METHODS AND RESULTS: After MI was induced by ligation of the coronary artery, C57BL/6 mice were intraperitoneally administered with one specific agonist or antagonist of the GABAA receptor (topiramate or bicuculline), in the setting of presence or depletion of monocytes/macrophages. Our data showed that within the first 2 weeks after MI, when monocytes/macrophages dominated, in contrast with bicuculline, topiramate treatment significantly reduced Ly-6Chigh monocyte numbers by regulating splenic monocytopoiesis and promoted foetal derived macrophages preservation and conversion of M1 to M2 or Ly-6Chigh to Ly-6Clow macrophage phenotype in the infarcted heart, though GABAAergic drugs failed to affect M1/M2 or Ly-6Chigh/Ly-6Clow macrophage polarization directly. Accordingly, pro-inflammatory activities mediated by M1 or Ly-6Chigh macrophages were decreased and reparative processes mediated by M2 or Ly-6Clow macrophages were augmented. As a result, post-infarction ventricular remodelling was attenuated, as reflected by reduced infarct size and increased collagen density within infarcts. Echocardiographic indices, mortality and rupture rates were reduced. After depletion of monocytes/macrophages by clodronate liposomes, GABAAergic drugs exhibited no effect on cardiac dysfunction and surrogate clinical outcomes. CONCLUSION: Control of the GABAA receptor activity in monocytes/macrophages can potently modulate post-infarction inflammation. Topiramate emerges as a promising drug, which may be feasible to translate for MI therapy in the future.

Left Heart Decompression in Acute Complicated Myocardial Infarction During Extracorporeal Membrane Oxygenation.

Acute myocardial infarction (AMI) can progress to cardiogenic shock and mechanical complications. When extracorporeal membrane oxygenation (ECMO) is applied to a patient with AMI with cardiogenic shock and mechanical complications, left ventricular (LV) decompression is an important recovery factor because LV dilation increases myocardial wall stress and oxygen consumption. The authors present the case of a 72-year-old man with AMI and LV dilation who developed cardiogenic shock and papillary muscle rupture and who was treated successfully by ECMO with a left atrial venting.

A Case of Post Myocardial Infarction Papillary Muscle Rupture.

Papillary muscle rupture is a rare, life-threatening post myocardial infarction mechanical complication. Without surgical intervention, prognosis is very poor. Clinicians need to recognize this complication early, as prompt therapy is crucial. We present a case of inferior ST elevation myocardial infarction complicated by posteromedial papillary muscle rupture resulting in severe acute mitral regurgitation (flail anterior mitral leaflet), acute pulmonary edema and cardiogenic shock. In our patient, a new mitral regurgitation murmur suggested this mechanical complication. Complete disruption of papillary muscle was visualized by transesophageal echocardiography. This case illustrates the importance of good physical examination for early diagnosis of papillary muscle rupture, so that life-saving treatment can be administered without delay.

Deletion of CD28 Co-stimulatory Signals Exacerbates Left Ventricular Remodeling and Increases Cardiac Rupture After Myocardial Infarction.

BACKGROUND: Inflammatory responses, especially by CD4(+)T cells activated by dendritic cells, are known to be important in the pathophysiology of cardiac repair after myocardial infarction (MI). Although co-stimulatory signals through B7 (CD80/86) and CD28 are necessary for CD4(+)T cell activation and survival, the roles of these signals in cardiac repair after MI are still unclear. METHODS AND RESULTS: C57BL/6 (Control) mice and CD28 knockout (CD28KO) mice were subjected to left coronary artery permanent ligation. The ratio of death by cardiac rupture within 5 days after MI was significantly higher in CD28KO mice compared with Control mice. Although there were no significant differences in the infarct size between the 2 groups, left ventricular end-diastolic and end-systolic diameters were significantly increased, and fractional shortening was significantly decreased in CD28KO mice compared with Control mice. Electron microscopic observation revealed that the extent of extracellular collagen fiber was significantly decreased in CD28KO mice compared with Control mice. The number of α-smooth muscle actin-positive myofibroblasts was significantly decreased, and matrix metalloproteinase-9 activity and the mRNA expression of interleukin-1ß were significantly increased in CD28KO mice compared with Control mice. CONCLUSIONS: Deletion of CD28 co-stimulatory signals exacerbates left ventricular remodeling and increases cardiac rupture after MI through prolongation of the inflammatory period and reduction of collagen fiber in the infarct scars. (Circ J 2016; 80: 1971-1979).