Neonatal myocardial infarction: case report and review of the literature

Regeneration of the heart: from molecular mechanisms to clinical therapeutics

Heart injury such as myocardial infarction leads to cardiomyocyte loss, fibrotic tissue deposition, and scar formation. These changes reduce cardiac contractility, resulting in heart failure, which causes a huge public health burden. Military personnel, compared with civilians, is exposed to more stress, a risk factor for heart diseases, making cardiovascular health management and treatment innovation an important topic for military medicine. So far, medical intervention can slow down cardiovascular disease progression, but not yet induce heart regeneration. In the past decades, studies have focused on mechanisms underlying the regenerative capability of the heart and applicable approaches to reverse heart injury. Insights have emerged from studies in animal models and early clinical trials. Clinical interventions show the potential to reduce scar formation and enhance cardiomyocyte proliferation that counteracts the pathogenesis of heart disease. In this review, we discuss the signaling events controlling the regeneration of heart tissue and summarize current therapeutic approaches to promote heart regeneration after injury.

Neonatal Myocardial Infarction: A Proposed Algorithm for Coronary Arterial Thrombus Management

BACKGROUND

Neonatal myocardial infarction is rare and is associated with a high mortality of 40% to 50%. We report our experience with neonatal myocardial infarction, including presentation, management, outcomes, and our current patient management algorithm.

METHODS

We reviewed all infants admitted with a diagnosis of coronary artery thrombosis, coronary ischemia, or myocardial infarction between January 2015 and May 2021.

RESULTS

We identified 21 patients (median age, 1 [interquartile range (IQR), 0.25-9.00] day; weight, 3.2 [IQR, 2.9-3.7] kg). Presentation included respiratory distress (16), shock (3), and murmur (2). Regional wall motion abnormalities by echocardiogram were a key criterion for diagnosis and were present in all 21 with varying degrees of depressed left ventricular function (severe [8], moderate [6], mild [2], and low normal [5]). Ejection fraction ranged from 20% to 54% (median, 43% [IQR, 34%-51%]). Mitral regurgitation was present in 19 (90%), left atrial dilation in 15 (71%), and pulmonary hypertension in 18 (86%). ECG was abnormal in 19 (90%). Median troponin I was 0.18 (IQR, 0.12-0.56) ng/mL. Median BNP (B-type natriuretic peptide) was 2100 (IQR, 924-2325) pg/mL. Seventeen had documented coronary thrombosis by cardiac catheterization. Seventeen (81%) were treated with intracoronary tPA (tissue-type plasminogen activator) followed by systemic heparin, AT (antithrombin), and intravenous nitroglycerin, and 4 (19%) were treated with systemic heparin, AT, and intravenous nitroglycerin alone. Nineteen of 21 recovered. One died (also had infradiaphragmatic total anomalous pulmonary venous return). One patient required a ventricular assist device and later underwent heart transplant; this patient was diagnosed late at 5 weeks of age and did not respond to tPA. Nineteen of 21 (90%) regained normal left ventricular function (ejection fraction, 60%-74%; mean, 65% [IQR, 61%-67%]) at latest follow-up (median, 6.8 [IQR, 3.58-14.72] months). Two of 21 (10%) had residual trivial mitral regurgitation. After analysis of these results, we present our current algorithm, which developed and matured over time, to manage neonatal myocardial infarction.

CONCLUSIONS

We experienced a lower mortality rate for infants with neonatal infarction than that reported in the literature. We propose a post hoc algorithm that may lead to improvement in patient outcomes following coronary artery thrombus.

Massive perinatal left ventricle infarction treated with tissue plasminogen activator: No ECMO - A case report

Neonatal myocardial infarction due to coronary thrombus is a rare cause of acute heart failure and is associated with high morbidity and mortality. We present a rare case of a full-term newborn who developed coronary artery thrombus treated with intracoronary recombinant tissue plasminogen activator infusion while undergoing therapeutic hypothermia. Also, we describe a unique treatment strategy to support systemic circulation sparing the patient from neonatal extracorporeal membrane oxygenation and its complications. Neonatal myocardial infarction should be suspected and ruled out in sick newborns.

Emergency treatment of thrombus in right coronary artery and aortic root in a newborn with acute myocardial infarction

Perinatal myocardial infarction caused by aortic root and coronary artery thrombosis in neonatal period is extremely rare and has a gloomy prognosis that may cause devastating complications. A 3-h newborn baby who had acute myocardial infarction findings on postnatal electrocardiography had a thrombus in the aortic root with hyperechogenic right coronary artery region, and impaired right ventricular functions on echocardiography. The patient was urgently operated and thrombus was successfully removed from the aortic root and the right coronary artery. In conclusion, for large thrombi posing a risk for embolization in the aortic root, an urgent surgical thrombectomy procedure should be performed.

A Brief History in Cardiac Regeneration, and How the Extra Cellular Matrix May Turn the Tide

Tissue homeostasis is perturbed by stressful events, which can lead to organ dysfunction and failure. This is particularly true for the heart, where injury resulting from myocardial infarction or ischemic heart disease can result in a cascading event ultimately ending with the loss of functional myocardial tissue and heart failure. To help reverse this loss of healthy contractile tissue, researchers have spent decades in the hopes of characterizing a cell source capable of regenerating the injured heart. Unfortunately, these strategies have proven to be ineffective. With the goal of truly understanding cardiac regeneration, researchers have focused on the innate regenerative abilities of zebrafish and neonatal mammals. This has led to the realization that although cells play an important role in the repair of the diseased myocardium, inducing cardiac regeneration may instead lie in the composition of the extra cellular milieu, specifically the extra cellular matrix. In this review we will briefly summarize the current knowledge regarding cell sources used for cardiac regenerative approaches, since these have been extensively reviewed elsewhere. More importantly, by revisiting innate cardiac regeneration observed in zebrafish and neonatal mammals, we will stress the importance the extra cellular matrix has on reactivating this potential in the adult myocardium. Finally, we will address how we can harness the ability of the extra cellular matrix to guide cardiac repair thereby setting the stage of next generation regenerative strategies.

The Regulatory Role of Oxygen Metabolism in Exercise-Induced Cardiomyocyte Regeneration

During heart failure, the heart is unable to regenerate lost or damaged cardiomyocytes and is therefore unable to generate adequate cardiac output. Previous research has demonstrated that cardiac regeneration can be promoted by a hypoxia-related oxygen metabolic mechanism. Numerous studies have indicated that exercise plays a regulatory role in the activation of regeneration capacity in both healthy and injured adult cardiomyocytes. However, the role of oxygen metabolism in regulating exercise-induced cardiomyocyte regeneration is unclear. This review focuses on the alteration of the oxygen environment and metabolism in the myocardium induced by exercise, including the effects of mild hypoxia, changes in energy metabolism, enhanced elimination of reactive oxygen species, augmentation of antioxidative capacity, and regulation of the oxygen-related metabolic and molecular pathway in the heart. Deciphering the regulatory role of oxygen metabolism and related factors during and after exercise in cardiomyocyte regeneration will provide biological insight into endogenous cardiac repair mechanisms. Furthermore, this work provides strong evidence for exercise as a cost-effective intervention to improve cardiomyocyte regeneration and restore cardiac function in this patient population.

Newborn With Severely Depressed Left Ventricular Function: Acute Myocardial Infarction in a Newborn

We describe a rare case of spontaneous coronary artery thrombosis in a newborn leading to rapid severe ventricular dysfunction. Early diagnosis is critical and management strategies are varied including hemodynamic support with extracorporeal membrane oxygenation, systemic/local thrombolytic therapy with tissue plasminogen activator, or surgical thrombectomy. (Level of Difficulty: Advanced.)

Myocardial Infarction in Neonates: A Diagnostic and Therapeutic Challenge

Neonatal acute myocardial infarction is an uncommon entity. We describe the case of a 4-day-old term baby who presented with respiratory distress and distal acrocyanosis. The chest radiograph demonstrated cardiomegaly without pleural effusion, and examination revealed hepatomegaly. An electrocardiogram revealed QS pattern in leads I, aVL, and V6, suggestive of ischemia. Cardiac enzymes were elevated, and echocardiogram revealed moderate left ventricular dysfunction with a thrombus at the level of the left atrial appendage. The patient required hemodynamic stabilization, vasodilatation to avoid congestive heart failure, and anticoagulation with heparin and aspirin. In the context of this unusual diagnosis, we reviewed our experience over the last 17 years as well as the existing literature on neonatal myocardial infarction.

Acute coronary artery obstruction following surgical repair of congenital heart disease

OBJECTIVES

Acute coronary artery obstruction is a rare complication of congenital heart disease surgery but imposes a high burden of morbidity and mortality. Previous case series have described episodes in specific congenital heart lesions or surgical repairs but have not examined the complication in all-comers to congenital heart surgery. We hypothesize that shorter time from a clinically recognized postoperative sentinel event suggestive of coronary ischemia to diagnosis of coronary obstruction is associated with improved clinical outcomes.

METHODS

This was a single-center, retrospective review of patients diagnosed with acute coronary artery obstruction by angiography following surgical repair of congenital heart disease between January 2000 and June 2016.

RESULTS

In total, 34 patients were identified. The most common procedures associated with coronary artery obstruction were the Norwood procedure, arterial switch operation, and aortic valve repair/replacement. In total, 79% required mechanical circulatory support, 41% died, and 27% were listed for heart transplant. Patients who died or were listed for heart transplant had longer median sentinel-event-to-cardiac-catheterization time (28 [6-168] hours vs 10 [3-56] hours, P = .001), and longer median sentinel-event-to-intervention time (32 [11-350] hours vs 13 [5-59] hours, P = .003). Patients with hypoplastic left heart syndrome were at greater risk of death or transplant listing (odds ratio, 9.23, P = .03).

CONCLUSIONS

Time from clinically relevant postoperative sentinel event to diagnosis of coronary artery obstruction by angiography was associated with transplant-listing-free survival. Clinicians should maintain a high index of suspicion for coronary obstruction and consider early catheterization and coronary angiography for patients in whom post-operative coronary compromise is suspected.

Postnatal Cardiac Development and Regenerative Potential in Large Mammals

The neonatal capacity for cardiac regeneration in mice is well studied and has been used to develop many potential strategies for adult cardiac regenerative repair following injury. However, translating these findings from rodents to designing regenerative therapeutics for adult human heart disease remains elusive. Large mammals including pigs, dogs, and sheep are widely used as animal models of humans in preclinical trials of new cardiac drugs and devices. However, very little is known about the fundamental cardiac cell biology and the timing of postnatal cardiac events that influence cardiomyocyte proliferation in these animals. There is emerging evidence that external physiological and environmental cues could be the key to understanding cardiomyocyte proliferative behavior. In this review, we survey available literature on postnatal development in various large mammal models to offer a perspective on the physiological and cellular characteristics that could be regulating cardiomyocyte proliferation. Similarities and differences between developmental milestones, cardiomyocyte maturational events, as well as environmental cues regulating cardiac development, are discussed for various large mammals, with a focus on postnatal cardiac regenerative potential and translatability to the human heart.

Oxygen as a key regulator of cardiomyocyte proliferation: New results about cell culture conditions!

The goal of the new therapeutically strategies aimed to treat cardiovascular diseases (CVDs) is to enhance the natural ability of the heart to regenerate. This represents a great challenge for the coming years as all the mechanisms underlying the replacement of dying cells by functional cells of the same type are not completely elucidated. Among these, stimulating cardiomyocyte proliferation seems to be crucial for the restoration of normal cardiac function after CVDs. In this review, we summarized the recent advances about the modulation of cardiomyocyte proliferation in physiological (during ageing) and pathological conditions. We highlighted the role of oxygen and we presented new results demonstrating that performing neonatal cardiomyocyte cell cultures in "normoxic" oxygen conditions (i.e. 3% oxygen) increases their proliferation rate, when compared to "hyperoxic" conventional conditions (i.e. 20% oxygen). Thus, oxygen concentration seems to be a key factor in the control of cardiomyocyte proliferation.

Early survival following in utero myocardial infarction

Intrauterine myocardial infarction is a rare and frequently fatal diagnosis. It has been presented in the literature only as case reports and short series. We present a case report of a coronary occlusive intrauterine myocardial infarction and survival and present a systematic review of the literature. This is the first summative description of current data on intrauterine and perinatal myocardial infarction. We performed the systematic review based on the guidelines established by the PRISMA statement. Our population of intrauterine and perinatal myocardial infarction included published cases who presented as a live birth within the first 28 postnatal days, and had a diagnosis of myocardial infarction. We conducted descriptive statistics and regression analysis on short-term mortality as the primary outcome. After applying exclusion criteria we described 84 individual cases of myocardial infarction from 63 full-text articles including our own case. Presentation within the first 12 hours was associated with mortality (OR 3.90, p=0.004). Treatment modalities were varied and inconsistently recorded. The aetiologies and comorbidities are varied in our systematic review. We would have a low threshold to perform viral testing, consider anticoagulation early and coronary imaging if feasible. The use of extracorporeal membranous oxygenation may serve as a bridge to cardiac recovery.

New Myocyte Formation in the Adult Heart: Endogenous Sources and Therapeutic Implications

Death of adult cardiac myocytes and supportive tissues resulting from cardiovascular diseases such as myocardial infarction is the proximal driver of pathological ventricular remodeling that often culminates in heart failure. Unfortunately, no currently available therapeutic barring heart transplantation can directly replenish myocytes lost from the injured heart. For decades, the field has struggled to define the intrinsic capacity and cellular sources for endogenous myocyte turnover in pursuing more innovative therapeutic strategies aimed at regenerating the injured heart. Although controversy persists to this day as to the best therapeutic regenerative strategy to use, a growing consensus has been reached that the very limited capacity for new myocyte formation in the adult mammalian heart is because of proliferation of existing cardiac myocytes but not because of the activity of an endogenous progenitor cell source of some sort. Hence, future therapeutic approaches should take into consideration the fundamental biology of myocyte renewal in designing strategies to potentially replenish these cells in the injured heart.

Surgical Management of Extensive Perinatal Myocardial Infarction

Extensive perinatal myocardial infarction caused by coronary artery thrombosis is extremely rare and has a dismal prognosis. We report a 3.5-kg neonate who presented at birth with an extensive myocardial infarction caused by aortic root and left main coronary artery thrombus after an emergency cesarean section. We performed emergency surgical thrombectomy and insertion of extracorporeal membrane oxygenation support. After subsequent conversion to long-term left ventricular assist device with an EXCOR device (Berlin Heart, Berlin, Germany), the patient had no ventricular recovery after 163 days of support. He was successfully bridged to transplantation.

Myocardial Infarction in Neonates: A Review of an Entity with Significant Morbidity and Mortality

Coronary artery disease is a global problem with high mortality rates and significant residual sequelae that affect long-term quality of life. Myocardial infarction (MI) in neonates is a recognized, uncommon entity, but the incidence and broad spectrum of the disease is unknown and likely underestimated due to limited reporting which in the majority is confined to acute ischemic events. The challenges involve clinical diagnosis which masquerades in the early phase as non-specific symptoms and signs that are commonly found in a host of neonatal disorders. Precise diagnostic criteria for neonatal MI are lacking, and management is driven by clinical presentation and hemodynamic stabilization rather than an attempt to rapidly establish the root cause of the condition. We conducted a review of the published reports of neonatal MI from 2000 to 2014, to establish an approach to the diagnosis and management based on the existing evidence. The overall evidence from 32 scientific articles stemmed from case reports and case series which were graded as low-to-very low quality. Neonatal MI resembles childhood and adult MI with features that involve characteristic ECG changes, raised biomarkers, and diagnostic imaging, but with lack of robust, standardized criteria to facilitate prompt diagnosis and timely intervention. The mortality rate of neonatal MI ranges from 40 to 50% based on inclusion criteria, but the short-term data reflect normal quality of life in survivors. An algorithm for the diagnosis and management of neonatal MI may optimize outcomes, but at the present time is based on limited evidence. Well-designed clinical studies focusing on the definition, diagnosis, and management of neonatal MI, backed by international consensus guidelines, are needed to alter the prognosis of this serious condition.

Tissue plasminogen activator for neonatal coronary thrombosis presenting with mitral valve regurgitation and impaired ventricular function

OBJECTIVE

Neonatal coronary thrombosis is a rarely reported disorder, with variable outcomes described. This study assessed the feasibility and safety of an institutional protocol using tissue plasminogen activator (tPA) administration for the treatment of neonatal coronary artery thrombi.

METHODS

They reviewed the outcome of three neonates with clinical evidence of myocardial infarction secondary to coronary thrombosis. All three underwent the tPA treatment protocol.

RESULTS

The three described cases presented at 5 hours, 15 hours, and 10 days of life. The patients identified underwent the tPA protocol at least once. There was clinical evidence of improvement in coronary flow, as well as demonstration of increased left ventricular function and decreased mitral regurgitation. No major adverse events occurred.

CONCLUSION

Thrombolytic therapy with this tPA protocol may be safe and effective in treating neonates with coronary thrombosis.

Acute myocardial infarction in a premature infant on the first day of life

Neonatal myocardial infarction (MI) is a very rare but potentially life-threatening condition with an approximated mortality rate of 80%. Congenital heart disease, anomalous coronary artery anatomy, thromboembolism, coagulopathy, birth asphyxia or myocarditis have been suggested as possible causes of MI. Here we report the case of a premature infant who died at about 40 h of life from a massive MI. Autopsy revealed an occlusive thrombus in the right coronary artery. An isolated prothrombotic status, characterized by a double copy variant of the MTHFR A1298C mutation, was identified at the postmortem genetic studies as a possible explanation for the coronary artery thrombosis. No other risk factors were detected.

Right Ventricular Myocardial Ischemia with Arrhythmia in an Asphyxiated Newborn

Background Infant and neonatal myocardial infarction (MI) has been described in association with congenital heart disease, coronary artery abnormalities, myocarditis, and tumors. MI in the perinatal period in a structurally normal heart and with ventricular arrhythmia as a presenting feature has not been thoroughly described. Published case reports describe treatment methods extrapolated from adult MI. However, due to the rare occurrence, the most appropriate acute treatment for both MI and ventricular arrhythmia in newborn infants remains unknown. Case A male term infant with perinatal asphyxia and need for extensive cardiopulmonary resuscitation at birth had ventricular tachyarrhythmia and ST-elevations on electrocardiogram. Four hours after birth, he died from cardiogenic failure. A thrombus at the right coronary artery was found on autopsy. Conclusion MI in the perinatal period in a structurally normal heart is very rare and mortality is high. Although acute treatments extrapolated from adult MI has been described to result in favorable outcomes in newborn infants, guidelines are lacking on how to manage acute MI and associated ventricular arrhythmia.

Functional Recovery of a Human Neonatal Heart After Severe Myocardial Infarction

RATIONALE

Cardiac remodeling and subsequent heart failure remain critical issues after myocardial infarction despite improved treatment and reperfusion strategies. Recently, cardiac regeneration has been demonstrated in fish and newborn mice after apex resection or cardiac infarctions. Two key issues remain to translate findings in model organisms to future therapies in humans: what is the mechanism and can cardiac regeneration indeed occur in newborn humans?

OBJECTIVE

To assess whether human neonatal hearts can functionally recover after myocardial infarction.

METHODS AND RESULTS

Here, we report the case of a newborn child having a severe myocardial infarction due to coronary artery occlusion. The child developed massive cardiac damage as defined by serum markers for cardiomyocyte cell death, electrocardiograms, echocardiography, and cardiac angiography. Remarkably, within weeks after the initial ischemic insult, we observed functional cardiac recovery, which translated into long-term normal heart function.

CONCLUSIONS

These data indicate that, similar to neonatal rodents, newborn humans might have the intrinsic capacity to repair myocardial damage and completely recover cardiac function.

A case of neonatal myocardial infarction: left coronary artery thrombus resolution and normalisation of ventricular function by intracoronary low-dose tissue plasminogen activator

Neonatal myocardial infarction is a rare clinical entity that is associated with high mortality. Reported treatment strategies include supportive care, extracorporeal membrane oxygenation, thrombolytics, and surgical thrombectomy. Herein we report a neonate who developed an acute myocardial infarction owing to a thrombus in the proximal left coronary artery. At 24 hours of life, he was treated with local (intracoronary) thrombolytic therapy at a lower dose than previously reported, as well as with systemic anticoagulation. There was subsequent angiographic resolution of the thrombus and normalisation of left ventricular function.

Erythrocytosis and severe asphyxia: two different causes of neonatal myocardial infarction

Neonatal acute myocardial infarction is a rare event that carries a high mortality rate. We describe the cases of two newborns who survived acute myocardial infarction and discuss the management. The first neonate was born with severe asphyxia and left ventricular myocardial infarction with ventricular tachycardia. In this patient, systemic flow was maintained by right-to-left shunting through the patent ductus arteriosus. The second neonate presented with a haematocrit of 80% and an inferolateral myocardial infarction. Intensive treatment of low cardiac output syndrome led to survival of both high-risk neonates. In the follow-up, at 48 and 4 months, respectively, ventricular function recovered in both patients.

Neonatal acute myocardial infarction of unknown etiology treated with surgical thrombectomy

Coronary artery thrombosis and resultant myocardial infarction in neonates are exceedingly rare. Seldom does a neonate survive this myocardial insult. Often there is an underlying predisposition to coronary artery thrombosis, such as thrombophilia, central line placement, or myocarditis. Treatment attempts have consisted of thrombolysis and supportive care. We present a case of acute left main coronary artery (LMCA) thrombosis of unknown etiology in a neonate, without ventricular dilatation. Flow into the LMCA was suggested echocardiographically, but a high clinical suspicion led to urgent cardiac catheterization. Once complete occlusion of the LMCA was demonstrated angiographically, emergent surgical thrombectomy was performed, which has never previously been reported.

Successful management of neonatal myocardial infarction with ECMO and intracoronary r-tPA lysis

Acute myocardial infarction (MI) is a life-threatening condition rarely encountered in neonates. The patients usually present with sudden cardiogenic shock. Clinical management in neonates is extremely challenging. If treatment is delayed, the prognosis is dismal. We report on a 4-day-old full-term male newborn presenting with acute MI and cardiogenic shock secondary to proximal thromboembolic occlusion of the left descending coronary artery. Hemodynamic stabilization could only be achieved after extracorporeal membrane oxygenation (ECMO) support. Coronary artery patency restoration was performed by selective intracoronary lysis with recombinant tissue plasminogen activator (r-tPA). ECMO support could be discontinued and myocardial function recovered within 6 weeks. We discuss the potential etiologies of acute perinatal MI and the role of ECMO support in the immediate post-MI period. Prompt recognition, timely referral to a cardiac center with availability of specialized advanced treatment options, and management in an orchestrated interdisciplinary approach are crucial for achieving a good outcome.