A real-world analysis of cardiac rupture on incidence, risk factors and in-hospital outcomes in 4190 ST-elevation myocardial infarction patients from 2004 to 2015

Diagnosis of post-myocardial infarction left ventricular rupture on CT

Myocardial rupture is often a catastrophic complication of acute myocardial infarction. Diagnosis can be challenging in the critically unwell patient. We present the case of a 70-year-old female who collapsed in the community with pulseless electrical activity, in cardiac arrest. She was transferred emergently to hospital where early resuscitation efforts were suggestive of a posterior myocardial infarct and severe blood loss. Point-of-care cardiac ultrasound demonstrated pericardial effusion but could not rule out aortic dissection. The patient underwent CT imaging with intravenous contrast which revealed left ventricular rupture secondary to the infarction. CT imaging can be a valuable diagnostic adjunct in patients with suspected post-infarction myocardial rupture.

Left ventricular free wall rupture: A real nightmare

Left ventricular free wall rupture (LVFWR) is a rarest but often lethal mechanical complication of acute myocardial infarction (AMI). The mortality rate for LVFWR is described from 75% to 90% and it is the cause for 20% of in-hospital deaths after AMI. Death results essentially from the limited time available for emergent intervention after onset of symptoms. Emergency surgery is indicated and normally the rupture site is easily identified, but it may not be apparent macroscopically, corresponding to transmyocardial or subepicardial dissection with an external rupture far from the infarction site, or already thrombosed and contained. Repair of the ventricular wall is usually achieved either by suturing the edges of the tear or closing it with patches of artificial material or biological tissues, usually using some kind of biological glue. However, several cases of successful conservative management have been described. In this Editorial, I comment on the metanalysis conducted by Matteucci et al, published in this issue of the Journal, including 11 nonrandomized studies and enrolling a total of 363 patients, which brings a great deal of new knowledge that can help not only in the prevention but also in the management of this dreadful complication of AMI.

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.

Recent insights into pathophysiology and management of mechanical complications of myocardial infarction

PURPOSE OF REVIEW

Mechanical complications of myocardial infarction are a group of postischemic events and include papillary muscle rupture resulting in ischemic mitral regurgitation, ventricular septal defect, left ventricle free wall rupture, pseudoaneurysm, and true aneurysm. Advances made in management strategies, such as the institution of 'Code STEMI' and percutaneous interventions, have lowered the incidence of these complications. However, their presentation is still associated with increased morbidity and mortality. Early diagnosis and appropriate management is crucial for facilitating better clinical outcomes.

RECENT FINDINGS

Although the exact timing of a curative intervention is not known, emerging percutaneous and transcatheter approaches and improving mechanical circulatory support (MCS) devices have greatly enhanced our ability to manage and treat some of the complications postinfarct.

SUMMARY

Although the incidence of mechanical complications of myocardial infarction has decreased over the past few decades, these complications are still associated with high rates of morbidity and mortality. The combination of early and accurate diagnosis and subsequent appropriate management are imperative for optimizing clinical outcomes. Although more randomized clinical trials are needed, mechanical circulatory support devices and emerging therapeutic strategies can be offered to carefully selected patients.

Validation of diagnostic criteria and histopathological characterization of cardiac rupture in the mouse model of nonreperfused myocardial infarction

In patients with myocardial infarction (MI), cardiac rupture is an uncommon but catastrophic complication. In the mouse model of nonreperfused MI, reported rupture rates are highly variable and depend not only on the genetic background and sex of animals but also on the method used for documentation of rupture. In most studies, diagnosis of cardiac rupture is based on visual inspection during autopsy; however, criteria are poorly defined. We performed systematic histopathological analysis of whole hearts from C57BL/6J mice dying after nonreperfused MI and evaluated the reliability of autopsy-based criteria in identification of rupture. Moreover, we compared the cell biological environment of the infarct between rupture-related and rupture-independent deaths. Histopathological analysis documented rupture in 50% of mice dying during the first week post-MI. Identification of a gross rupture site was highly specific but had low sensitivity; in contrast, hemothorax had high sensitivity but low specificity. Mice with rupture had lower myofibroblast infiltration, accentuated macrophage influx, and a trend toward reduced collagen content in the infarct. Male mice had increased mortality and higher incidence of rupture. However, infarct myeloid cells harvested from male and female mice at the peak of the incidence of rupture had comparable inflammatory gene expression. In conclusion, the reliability of autopsy in documentation of rupture in infarcted mice is dependent on the specific criteria used. Macrophage-driven inflammation and reduced activation of collagen-secreting reparative myofibroblasts may be involved in the pathogenesis of post-MI cardiac rupture.NEW & NOTEWORTHY We show that cardiac rupture accounts for 50% of deaths in C57BL/6J mice undergoing nonreperfused myocardial infarction protocols. Overestimation of rupture events in published studies likely reflects the low specificity of hemothorax as a criterion for documentation of rupture. In contrast, identification of a gross rupture site has high specificity and low sensitivity. We also show that mice dying of rupture have increased macrophage influx and attenuated myofibroblast infiltration in the infarct. These findings are consistent with a role for perturbations in the balance between inflammatory and reparative responses in the pathogenesis of postinfarction cardiac rupture. We also report that the male predilection for rupture in infarcted mice is not associated with increased inflammatory activation of myeloid cells.