Systematic review of patients presenting with suspected myocardial infarction and nonobstructive coronary arteries

Nonobstructive Versus Obstructive Coronary Artery Disease in Acute Coronary Syndrome: A Meta-Analysis

Background

Differences in prognosis and baseline clinical presentation have been documented among patient with acute coronary syndrome and coronary artery disease with obstructive (ObCAD) or nonobstructive arteries (NObCAD), but the rates of events largely varied across single studies. We carried out a meta‐analysis to compare the clinical presentation and prognosis of NObCAD versus ObCAD acute coronary syndrome patients, as well as of the subjects with zero versus mild occlusion.

Methods and Results

Searches were made in MedLine, EMBASE, Cochrane databases, and proceedings of international meetings up to June 30, 2015. We compared the risk of events of NObCAD versus ObCAD patients using random‐effect meta‐analyses. We also performed meta‐analyses to estimate the yearly or monthly outcome rates in each single group. In NObCAD and ObCAD patients, respectively, the combined yearly rates were as follows: 2.4% versus 10.1% (all‐cause mortality); 1.2% versus 6.0% (myocardial infarction), 4.0% versus 12.8% (all‐cause mortality plus myocardial infarction), 1.4% versus 5.9% (cardiac death), and 9.2% versus 16.8% (major cardiovascular events). In the studies directly comparing NObCAD versus ObCAD, all of the above outcomes were significantly less frequent in NObCAD subjects (with risk ratios ranging from 0.33 to 0.66). No differences in any outcome rate were observed between mild occlusion (1–49% stenosis) and zero occlusion patients.

Conclusions

NObCAD in patients with acute coronary syndrome has a significantly lower cardiovascular risk at baseline and a subsequent lower likelihood of death or main cardiovascular events. However, these subjects are still at high risk for cardiovascular mortality and morbidity, suggesting potential undertreatment and calling for specific management.

IRAP inhibition using HFI419 prevents moderate to severe acetylcholine mediated vasoconstriction in a rabbit model

Coronary artery vasospasm (constriction) caused by reduced nitric oxide bioavailability leads to myocardial infarction. Reduced endothelial release of nitric oxide by the neurotransmitter acetylcholine, leads to paradoxical vasoconstriction as it binds to smooth muscle cell M3 receptors. Thus, inhibition of coronary artery vasospasm will improve clinical outcomes. Inhibition of insulin regulated aminopeptidase has been shown to improve vessel function, thus we tested the hypothesis that HFI419, an inhibitor of insulin regulated aminopeptidase, could reduce blood vessel constriction to acetylcholine. The abdominal aorta was excised from New Zealand white rabbits (n=15) and incubated with 3mM Hcy to induce vascular dysfunction in vitro for 1h. HFI419 was added 5min prior to assessment of vascular function by cumulative doses of acetylcholine. In some rings, vasoconstriction to acetylcholine was observed in aortic rings after pre-incubation with 3mM homocysteine. Incubation with HFI419 inhibited the vasoconstrictive response to acetylcholine, thus improving, but not normalizing, vascular function (11.5±8.9% relaxation vs 79.2±37% constriction, p<0.05). Similarly, in another group with mild vasoconstriction, HFI419 inhibited this effect (34.9±4.6% relaxation vs 11.1±5.2%, constriction, p<0.05). HFI419 had no effect on control aorta or aorta with mild aortic dysfunction. The present study shows that HFI419 prevents acetylcholine mediated vasoconstriction in dysfunctional blood vessels. HFI419 had no effect on normal vasodilation. Our results indicate a therapeutic potential of HFI419 in reducing coronary artery vasospasm.

The role of MRI and CT for diagnosis and work-up in suspected ACS

This article describes the role of cardiovascular magnetic resonance (CMR) and cardiac computed tomography (CCT) in the diagnostic work-up of patients with suspected acute coronary syndrome (ACS). Recent studies on the principles, diagnostic targets, clinical utility, accuracy, prognostic relevance and implications for clinical decision-making are discussed and current state-of-the-art and novel approaches are presented. The authors recognize that in ACS, time is of the essence and therefore put a special emphasis on the feasibility of tomographic cardiac imaging in realistic clinical settings.

Advanced Imaging and Diagnostic Methods in the Assessment of Suspected Ischemic Heart Disease in Women

Although differences diminish with age, outcomes are overall worse for women compared to men who present with suspected acute coronary syndrome. The reasons for this discrepancy are multifactorial, including sex-related differences in atherosclerosis biology and fluid dynamics, as well as a premature conclusion by providers that chest pain must be noncardiac in the absence of obstructive coronary artery disease. In this review of existing literature, we explore the diverse differential diagnosis in this unique set of patients. Especially in women with persistent symptoms, absence of occlusive disease should prompt consideration for subangiographic plaque disruption, epicardial or microvascular endothelial dysfunction, transient neurohormonal imbalance predisposing to Takotsubo cardiomyopathy or spontaneous coronary artery dissection, underlying systemic inflammatory conditions, thromboembolic disease, myocarditis, and sequelae of congenital heart disease. As always, a thorough history and attentive physical exam will help guide further work-up, which in many cases may warrant noninvasive imaging, such as contrast-enhanced echocardiography, cardiac magnetic resonance imaging, or positron emission tomography, with their respective means of measuring myocardial perfusion and myocardial tissue pathology. Lastly, intracoronary imaging such as intravascular ultrasound and optical coherence tomography and invasive diagnostic methods such as coronary reactivity testing continue to add to our understanding that what appear to be atypical presentations of ischemic heart disease in women may in fact be typical presentations of pathologic cousin entities that remain incompletely defined.

Impact of aspirin on the prognosis in patients with coronary spasm without significant atherosclerotic stenosis

BACKGROUND

Coronary spasm is one of the mechanisms of myocardial infarction with nonobstructive coronary arteries (MINOCA). The aim of this study was to investigate the effects of aspirin on future cardiovascular events in patients with coronary vasospastic angina (VSA) with non-significant atherosclerotic stenosis.

METHODS

This was the retrospective analysis of the 640 VSA patients with non-significant atherosclerotic stenosis (≤50% stenosis) among 1,877 consecutive patients who underwent acetylcholine (ACh)-provocation testing between January 1991 and December 2010. The patients were divided into 2 groups treated with (n=137) or without (n=503) low-dose aspirin (81-100mg/day). We evaluated major adverse cardiac events (MACE), defined as cardiac death, nonfatal myocardial infarction, and unstable angina.

RESULTS

In the study population, 24 patients (3.8%) experienced MACE; there were 6 cases in VSA patients with aspirin and 6 in those without aspirin. Multivariate Cox hazards analysis for correlated factors of MACE indicated that use of statin (HR: 0.11; 95% CI: 0.02 to 0.84; P=0.033), ST-segment elevation during attack (HR: 5.28; 95% CI: 2.19-12.7; P<0.001), but not the use of aspirin as a significant predictor of MACE. After propensity score matching (n=112, each), Kaplan-Meier survival analysis indicated almost identical rate of 5-year survival free from MACE in those with aspirin, compared to those without aspirin in the entire and matched cohort (P=0.640 and P=0.541, respectively).

CONCLUSIONS

Low-dose aspirin might not reduce future cardiovascular events in VSA patients with non-significant stenosis.

Incidence, Characteristics, Risk Factors, and Outcomes of Takotsubo Cardiomyopathy With and Without Ventricular Arrhythmia

Takotsubo cardiomyopathy (TC) is a medical entity mimicking an acute coronary syndrome (ACS). Ventricular arrhythmia (VA) in TC has been reported in small studies, leading to uncertain knowledge of its incidence. We sought to describe the characteristics, incidence, predictive factors, and outcomes of VA in patients presenting with TC. Over a 12-year period, we reviewed all patients (n = 5,484) referred to our coronary care unit for a suspicion of ACS. TC was diagnosed in 90 patients according to the Mayo Clinic criteria. Incidence of VA among TC was 10%. In multivariate analysis, the factors significantly associated with an increased risk of VA were syncope (p = 0.007), age <55 years (p = 0.008), atypical TC (p = 0.04), a troponin I peak >7 μg/L (p = 0.04), and dobutamine use during hospitalization (p = 0.04). During follow-up, there was no significant difference in mortality rate between patients with or without VA. In conclusion, VA occurred in 10% of patients at the acute phase of TC and independent predictive factors of VA were syncope, atypical pattern of TC, high troponin peak, dobutamine use, and a relatively young age in a female and menopausal population. During the acute phase, identification of high-risk patients with VA allows better management, with electrocardiographic monitoring and therapeutic intervention in the coronary care unit.

Cardiovascular Disease in Women: Clinical Perspectives

Cardiovascular disease continues to be the leading cause of death among women in the United States, accounting for ≈1 of every 3 female deaths. Sex-specific data focused on cardiovascular disease have been increasing steadily, yet is not routinely collected nor translated into practice. This comprehensive review focuses on novel and unique aspects of cardiovascular health in women and sex differences as they relate to clinical practice in the prevention, diagnosis, and treatment of cardiovascular disease. This review also provides current approaches to the evaluation and treatment of acute coronary syndromes that are more prevalent in women, including myocardial infarction associated with nonobstructive coronary arteries, spontaneous coronary artery dissection, and stress-induced cardiomyopathy (Takotsubo Syndrome). Other cardiovascular disease entities with higher prevalence or unique considerations in women, such as heart failure with preserved ejection fraction, peripheral arterial disease, and abdominal aortic aneurysms, are also briefly reviewed. Finally, recommendations for cardiac rehabilitation are addressed.

Impact on Long-Term Mortality of Presence of Obstructive Coronary Artery Disease and Classification of Myocardial Infarction

BACKGROUND

In contrast to the associated-with-thromboembolic-event type 1 myocardial infarction, type 2 myocardial infarction is caused by acute imbalance between oxygen supply and demand of myocardium. Type 2 myocardial infarction may be present in patients with or without obstructive coronary artery disease, but knowledge about patient characteristics, treatments, and outcome in relation to coronary artery status is lacking. We aimed to compare background characteristics, triggering mechanisms, treatment, and long-term prognosis in a large real-life cohort of patients with type 1 and type 2 myocardial infarction with and without obstructive coronary artery disease.

METHODS

All 41,817 consecutive patients with type 1 and type 2 myocardial infarction registered in the Swedish myocardial infarction registry (SWEDEHEART) who underwent coronary angiography between January 1, 2011 and December 31, 2013, with the last follow-up on December 31, 2014, were studied.

RESULTS

In 92.8% of 40,501 patients classified as type 1 and in 52.5% of patients classified as type 2 myocardial infarction, presence of an obstructive coronary artery disease could be shown. Within the patients with obstructive coronary artery disease, those with type 2 myocardial infarction were older, and had more comorbidities and smaller necrosis as compared with type 1 myocardial infarction. In contrast, there was almost no difference in risk profile and extent of myocardial infarction between type 1 and type 2 myocardial infarction patients with nonobstructive coronary artery stenosis. The crude long-term mortality was higher in type 2 as compared with type 1 myocardial infarction with obstructive coronary artery disease (hazard ratio [HR] 1.72; 95% confidence interval [CI], 1.45-2.03), but was lower after adjustment (HR 0.76; 95% CI, 0.61-0.94). In myocardial infarction patients with nonobstructive coronary artery stenosis, the mortality risk was similar regardless of the clinical myocardial infarction type (crude HR 1.14; 95% CI, 0.84-1.55; adjusted HR 0.82; 95% CI, 0.52-1.29).

CONCLUSIONS

The substantial differences in risk factors, treatment, and outcome in patients with type 1 and type 2 myocardial infarction with obstructive coronary artery disease supports the relevance of the division between type 1 and type 2 in this population. On the contrary, in patients with nonobstructive coronary artery stenosis, irrespective of the clinical type, a similar risk profile, extent of necrosis, and long-term prognosis were observed, indicating that distinction between type 1 and type 2 myocardial infarction in these patients seems to be inappropriate.

[Myocarditis in the differential diagnosis of cardiomyopathies. Endomyocardial biopsy or MRI?]

Myocarditis is an inflammatory disease of the heart muscle commonly caused by viral pathogens. Dilated cardiomyopathy is a major long-term sequela of myocarditis and at least in part related to post-viral immune-mediated responses. Establishing a diagnosis of myocarditis represents a major challenge because of the variable clinical picture and the lack of readily available, non-invasive diagnostic tests. In recent years, cardiac magnetic resonance imaging (cMRI) has emerged as a promising additional diagnostic tool in patients with suspected myocarditis: cMRI not only provides important insights into structural and functional abnormalities of the heart but relevant tissue pathologies can also be visualized. The diagnostic accuracy of three tissue criteria, i.e. the edema ratio, early gadolinium enhancement ratio and late gadolinium enhancement, has been characterized in several studies. Endomyocardial biopsy (EMB) is widely considered to be the reference standard for diagnosis of myocarditis. Although limited by sampling error, EMB is the only diagnostic procedure that can be used to confirm myocarditis. Laboratory analyses of EMB may provide information about specific causes of myocarditis and are, at least in part, of prognostic relevance. In a subset of patients the results of EMB may guide therapeutic decision-making. Additional efforts are needed in cardiac imaging, molecular characterization of EMB and evaluation of serum biomarkers to improve the diagnostic work-up in patients with suspected myocarditis and to identify potential novel targets for a cause-specific therapy of myocarditis.

Obstructive coronary artery disease in patients hospitalized for severe sepsis or septic shock with concomitant acute myocardial infarction

PURPOSE

It is difficult to differentiate type 1 acute myocardial infarction (AMI) with obstructive coronary artery disease (OCAD) from type 2 AMI in patients admitted for severe sepsis. The aims of this study were to assess the risk factors and prognosis of OCAD in patients admitted to the intensive care unit for severe sepsis with concomitant AMI.

MATERIALS AND METHODS

This is a single-center retrospective cohort study including all consecutive patients who were hospitalized for severe sepsis or septic shock between March 2006 and September 2014 and who underwent coronary angiography in the intensive care unit to identify AMI.

RESULTS

Overall, 78 (5.5%) of 1418 patients hospitalized for severe sepsis underwent coronary angiography to identify concomitant AMI. Thirty-two patients (41%) had OCAD. Following multivariate analysis, the risk factors of OCAD were peripheral vascular disease (odds ratio [OR] =5.7; 95% confidence interval [CI], 1.1-30.4; P = .042) and at least 2 cardiovascular risk factors (OR = 6.7; 95% CI, 1.9-23.8; P = .003). Obstructive coronary artery disease was associated with a significant mortality increase at 60 days (OR = 8.1; 95% CI, 1.9-30.2; P = .004).

CONCLUSIONS

Obstructive coronary artery disease is a poor prognosis factor in patients hospitalized for severe sepsis with concomitant AMI. In this setting, medical treatment should be considered for patients with peripheral vascular disease or with at least 2 cardiovascular risk factors; the need to perform coronary angiography should be considered carefully.

Enhanced p122RhoGAP/DLC-1 Expression Can Be a Cause of Coronary Spasm

Background

We previously showed that phospholipase C (PLC)-δ1 activity was enhanced by 3-fold in patients with coronary spastic angina (CSA). We also reported that p122Rho GTPase-activating protein/deleted in liver cancer-1 (p122RhoGAP/DLC-1) protein, which was discovered as a PLC-δ1 stimulator, was upregulated in CSA patients. We tested the hypothesis that p122RhoGAP/DLC-1 overexpression causes coronary spasm.

Methods and Results

We generated transgenic (TG) mice with vascular smooth muscle (VSM)-specific overexpression of p122RhoGAP/DLC-1. The gene and protein expressions of p122RhoGAP/DLC-1 were markedly increased in the aorta of homozygous TG mice. Stronger staining with anti-p122RhoGAP/DLC-1 in the coronary artery was found in TG than in WT mice. PLC activities in the plasma membrane fraction and the whole cell were enhanced by 1.43 and 2.38 times, respectively, in cultured aortic vascular smooth muscle cells from homozygous TG compared with those from WT mice. Immediately after ergometrine injection, ST-segment elevation was observed in 1 of 7 WT (14%), 6 of 7 heterozygous TG (84%), and 7 of 7 homozygous TG mice (100%) (p<0.05, WT versus TGs). In the isolated Langendorff hearts, coronary perfusion pressure was increased after ergometrine in TG, but not in WT mice, despite of the similar response to prostaglandin F_2α between TG and WT mice (n = 5). Focal narrowing of the coronary artery after ergometrine was documented only in TG mice.

Conclusions

VSM-specific overexpression of p122RhoGAP/DLC-1 enhanced coronary vasomotility after ergometrine injection in mice, which is relevant to human CSA.

The Variation in Recovery: Role of Gender on Outcomes of Young AMI Patients (VIRGO) Classification System: A Taxonomy for Young Women With Acute Myocardial Infarction

BACKGROUND

Current classification schemes for acute myocardial infarction (AMI) may not accommodate the breadth of clinical phenotypes in young women.

METHODS AND RESULTS

We developed a novel taxonomy among young adults (≤55 years) with AMI enrolled in the Variation in Recovery: Role of Gender on Outcomes of Young AMI Patients (VIRGO) study. We first classified a subset of patients (n=600) according to the Third Universal Definition of MI using a structured abstraction tool. There was heterogeneity within type 2 AMI, and 54 patients (9%; including 51 of 412 women) were unclassified. Using an inductive approach, we iteratively grouped patients with shared clinical characteristics, with the aims of developing a more inclusive taxonomy that could distinguish unique clinical phenotypes. The final VIRGO taxonomy classified 2802 study participants as follows: class 1, plaque-mediated culprit lesion (82.5% of women; 94.9% of men); class 2, obstructive coronary artery disease with supply-demand mismatch (2a: 1.4% women; 0.9% men) and without supply-demand mismatch (2b: 2.4% women; 1.1% men); class 3, nonobstructive coronary artery disease with supply-demand mismatch (3a: 4.3% women; 0.8% men) and without supply-demand mismatch (3b: 7.0% women; 1.9% men); class 4, other identifiable mechanism (spontaneous dissection, vasospasm, embolism; 1.5% women, 0.2% men); and class 5, undetermined classification (0.8% women, 0.2% men).

CONCLUSIONS

Approximately 1 in 8 young women with AMI is unclassified by the Universal Definition of MI. We propose a more inclusive taxonomy that could serve as a framework for understanding biological disease mechanisms, therapeutic efficacy, and prognosis in this population.

The Role of Cardiac MRI in Patients with Troponin-Positive Chest Pain and Unobstructed Coronary Arteries

Acute coronary syndrome (ACS) still remains one of the leading causes of mortality and morbidity worldwide. Seven to fifteen percent of patients presenting with ACS have unobstructed coronary artery disease (CAD) on urgent angiography. Patients with ACS and unobstructed coronary arteries represent a clinical dilemma and their diagnosis and management is quite variable in current practice. Cardiovascular magnetic resonance imaging with its unique non-invasive myocardial tissue characterization property has the potential to identify underlying etiologies and reach a final diagnosis. These include acute and chronic myocarditis, embolic/spontaneous recanalization myocardial infarction, and Tako-Tsubo cardiomyopathy, and other conditions. Establishing a final diagnosis has a direct implication on patient's management and prognosis. In this article, we have reviewed the current evidence on the diagnostic role of cardiac magnetic resonance (CMR) in patients with ACS and unobstructed coronary arteries. We have also highlighted the potential role of CMR as a risk stratification or prognostication tool for this patient population.

Incidence and characteristics of patients presenting with acute myocardial infarction and non-obstructive coronary artery disease

OBJECTIVES

This study aimed to characterize the etiologies of patients presenting with myocardial infarction (MI) and found to have non-obstructive coronary artery disease (NOCAD) and compare risk factors and in-hospital mortality to those with obstructive coronary artery disease (CAD).

BACKGROUND

Patients presenting with an MI are often found to have NOCAD defined as less than 50% luminal diameter reduction by visual estimation on coronary angiography.

METHODS

This study is a retrospective analysis of a total of 2,038 patients that presented to NorthShore University HealthSystem with MI and underwent coronary angiography from 2010 to 2013.

RESULTS

1,822 patients (89%) had CAD and 216 (11%) had NOCAD. Of the NOCAD patients, the most common etiologies were Takotsubo cardiomyopathy (28%), no alternative explanation (26%), demand ischemia (21%), myopericarditis (7%), coronary artery vasospasm (5%), and coronary artery dissection (3%). NOCAD patients were more likely to be younger and female. There was no significant difference between NOCAD and CAD patients in terms of in-hospital mortality (3.7% vs. 4.0% respectively, OR = 1.1, 95% CI 0.5-2.3, P = 0.83 by univariate logistic regression, OR = 1.2, 95% CI 0.5-3.1, P = 0.74 by multivariable analysis).

CONCLUSIONS

CAD patients were more likely to have traditional risk factors of diabetes, hypertension, hypercholesterolemia, previous MI, previous revascularization with percutaneous coronary intervention or coronary artery bypass graft surgery. Patients presenting with MI and NOCAD were found to have several different etiologies on coronary angiography with the most common being Takotsubo cardiomyopathy.

Myocardial Infarction With Non-obstructive Coronary Arteries - Diagnosis and Management

MI with non-obstructive coronary arteries (MINOCA) is an enigma that is being increasingly recognised with the frequent use of angiography following acute MI. To diagnose this condition, it is important to determine the multiple potential underlying mechanisms that may be responsible, many of which require different treatments. This review evaluates the contemporary diagnosis and management of MINOCA.