Myocardial Infarction Without Obstructive Coronary Artery Disease (MINOCA): A Practical Guide for Clinicians

Coronary microvascular dysfunction and myocardial infarction with non-obstructive coronary arteries: Where do we stand?

In the past decade, scientific and clinical research has provided a translational perspective on myocardial infarction (MI) with non-obstructive coronary arteries (MINOCA). MINOCA is characterized by clinical documentation of an acute MI but angiography shows no significant coronary artery obstruction (stenosis <50%). The prevalence of MINOCA is estimated to range from approximately 6 to 10% among MI patients, and those with this condition have a poor prognosis, experiencing high rates of mortality, rehospitalization, and socioeconomic burden. MINOCA represents a major unmet need in cardiovascular medicine, with uncertain clinical management. It is a complex condition that can be caused by various factors, including atherosclerosis, plaque rupture, coronary vasospasm, and microvascular dysfunction. Effective management of MINOCA depends on identifying the underlying mechanism of the infarction, thus a systematic diagnostic approach is recommended. Contemporary data shows that a significant number of patients exhibit structural and functional abnormalities in coronary microcirculation, which is referred to as coronary microvascular dysfunction (CMD). CMD plays a crucial role in patients with signs and symptoms of myocardial ischemia and non-obstructive coronary artery stenosis, including MINOCA. Furthermore, conducting a thorough evaluation of coronary function can have significant prognostic and therapeutic implications, since personalized patient management strategies based on this assessment have been shown to improve symptoms and prognosis. Therefore, an accurate and timely diagnosis of CMD is essential for effective patient management, which can be achieved through various invasive and non-invasive methods. This review will discuss the pathophysiological understanding, current diagnostic techniques, and management strategies of patients with MINOCA and CMD.

Characteristics of patients with recurrent acute myocardial infarction after MINOCA

BACKGROUND

Myocardial infarction (MI) with non-obstructed coronary arteries (MINOCA) is an increasingly recognized condition with challenging management. Some MINOCA patients ultimately experience recurrent acute MI (re-AMI) during follow-up; however, clinical and angiographic factors predisposing to re-AMI are still poorly defined.

METHODS

In this retrospective multicenter cohort study we enrolled consecutive patients fulfilling diagnostic criteria of MINOCA according to the IV universal definition of myocardial infarction; characteristics of patients experiencing re-AMI during the follow-up were compared to a group of MINOCA patients without re-AMI.

RESULTS

54 patients (mean age 66 ± 13) experienced a subsequent re-AMI after MINOCA and follow-up was available in 44 (81%). Compared to MINOCA patients without re-AMI (n = 695), on first invasive coronary angiography (ICA) MINOCA patients with re-AMI showed less frequent angiographically normal coronaries (37 versus 53%, p = 0.032) and had a higher prevalence of atherosclerosis involving 3 vessels or left main stem (17% versus 8%, p = 0.049). Twenty-four patients (44%) with re-AMI underwent a new ICA: 25% had normal coronary arteries, 12.5% had mild luminal irregularities (<30%), 20.8% had moderate coronary atherosclerosis (30-49%), and 41.7% showed obstructive coronary atherosclerosis (≥50% stenosis). Among patients undergoing new ICA, atherosclerosis progression was observed in 11 (45.8%), 37.5% received revascularization, only 4.5% had low-density lipoprotein cholesterol (LDL_C) under 55 mg/dL and 33% experienced a new cardiovascular disease (CVD) event (death, AMI, heart failure, stroke) at subsequent follow-up.

CONCLUSIONS

In the present study, only a minority of MINOCA patients with re-AMI underwent a repeated ICA, nearly one out of two showed atherosclerosis progression, often requiring revascularization. Recommended LDL-C levels were achieved only in a minority of the cases, indicating a possible underestimation of CVD risk in this population.

Characteristics and Prognosis of a Contemporary Cohort with Myocardial Infarction with Non-Obstructed Coronary Arteries (MINOCA) Presenting Different Patterns of Late Gadolinium Enhancements in Cardiac Magnetic Resonance Imaging

BACKGROUND

To analyze the characteristics and prognosis of a contemporary cohort of patients with myocardial infarction with non-obstructed coronaries (MINOCA) were referred for cardiac magnetic resonance (CMR) imaging, focusing on late gadolinium enhancement (LGE) patterns.

METHODS

We retrospectively examined and prospectively followed up with 135 patients (49 ± 21 years old, 48% female) undergoing CMR imaging due to a MINOCA diagnosis from 2014 to 2016. We grouped and analyzed the sample according to ischemic (focal or transmural) and non-ischemic LGE patterns. The primary outcome was cardiac-related death; the secondary outcome was a composite of cardiac-related rehospitalizations, the new occurrence of acute myocardial infarction (AMI), heart failure (HF), or arrhythmias.

RESULTS

CMR exams were performed after a median of 28 days from the acute event. One-third of the ischemic MINOCA were first managed as myocarditis, while CMR helped to adopt a different therapy regimen in 22% of patients (30/135). After a median follow-up of 2.3 years, more cardiac-related deaths occurred in the ischemic than non-ischemic group (2 vs. 1, p = 0.36), but it was not statistically significant. The ischemic group also experienced more cardiac-related-rehospitalizations (42%, p < 0.001). In a multivariable Cox regression model, dyslipidemia, reduced left ventricular ejection fraction, ST-elevation at the hospitalization, and the LGE transmural pattern were the independent predictors of cardiac-related rehospitalizations.

CONCLUSIONS

In a contemporary cohort of MINOCA patients who underwent CMR, ischemic and non-ischemic patterns had distinct features and outcomes. Among the MINOCA patients, CMR can identify patients at higher risk who require more aggressive therapeutic approached and strict follow-up.

Antiplatelet therapy in patients with myocardial infarction with non-obstructive coronary arteries: A clinical perspective

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a heterogeneous group of diseases with different pathological mechanisms, and it is uncertain whether the classical secondary prevention and treatment strategies for myocardial infarction in obstructive coronary artery disease (MI-CAD) are appropriate for patients with MINOCA. Therefore the choice of antiplatelet agents and the therapeutic effect may vary depending on the etiology and pathophysiological mechanisms of MINOCA. This requires our clinical and scientific researchers to properly design prospective studies to explore the pathophysiology of MINOCA and its corresponding etiology in greater depth, so as to understand the effectiveness and safety of medical therapies for different etiologies of MINOCA. Although the current observational studies do not show an obvious beneficial effect of antiplatelet therapy on MINOCA. We are eager to conduct specific prospective randomized controlled trials of antiplatelet agents to assess the specificity, efficacy and safety of different types of antiplatelet agents in patients with MINOCA of different etiologies.

Angina in 2022: Current Perspectives

Angina is the main symptom of ischemic heart disease; mirroring a mismatch between oxygen supply and demand. Epicardial coronary stenoses are only responsible for nearly half of the patients presenting with angina; whereas in several cases; symptoms may underlie coronary vasomotor disorders; such as microvascular dysfunction or epicardial spasm. Various medications have been proven to improve the prognosis and quality of life; representing the treatment of choice in stable angina and leaving revascularization only in particular coronary anatomies or poorly controlled symptoms despite optimal medical therapy. Antianginal medications aim to reduce the oxygen supply-demand mismatch and are generally effective in improving symptoms; quality of life; effort tolerance and time to ischemia onset and may improve prognosis in selected populations. Since antianginal medications have different mechanisms of action and side effects; their use should be tailored according to patient history and potential drug-drug interactions. Angina with non-obstructed coronary arteries patients should be phenotyped with invasive assessment and treated accordingly. Patients with refractory angina represent a higher-risk population in which some therapeutic options are available to reduce symptoms and improve quality of life; but robust data from large randomized controlled trials are still lacking.

Do Patients with Myocardial Infarction with Non-Obstructive Coronary Arteries Have Similar Prognosis Compared to Ones with MI-CAD?

Acute myocardial infarction (AMI) is a leading cause of morbidity and mortality worldwide and it is primarily caused by acute plaque disruption and coronary occlusion. Recent studies suggest that myocardial infarction with non-obstructive coronary arteries (MINOCA) also occurs but the underlying mechanisms have not been fully understood until recently. The evidence also suggests that the clinical outcomes of patients presenting with MINOCA are similar to AMI patients with obstructive coronary artery disease (MI-CAD), including all-cause mortality and major adverse cardiovascular events. The present narrative review considers the risk factors, pathological changes, and outcomes associated with MINOCA and compares them with MI-CAD.

Statin Use in Cancer Patients with Acute Myocardial Infarction and Its Impact on Long-Term Mortality

Statin use and its impact on long-term clinical outcomes in active cancer patients following acute myocardial infarction (MI) remains insufficiently elucidated. Of the 1011 consecutive acute MI patients treated invasively between 2012 and 2017, cancer was identified in 134 (13.3%) subjects. All patients were observed within a median follow-up of 69.2 (37.8−79.9) months. On discharge, statins were prescribed less frequently in MI patients with cancer as compared to the non-cancer MI population (79.9% vs. 91.4%, p < 0.001). The most common statin in both groups was atorvastatin. The long-term mortality was higher in MI patients not treated vs. those treated with statins, both in non-cancer (29.5%/year vs. 6.7%/year, p < 0.001) and cancer groups (53.9%/year vs. 24.9%/year, p < 0.05), respectively. Patient’s age (hazard ratio (HR) 1.04, 95% confidence interval (CI) 1.03−1.05, p < 0.001, per year), an active cancer (HR 2.42, 95% CI 1.89−3.11, p < 0.001), hemoglobin level (HR 1.14, 95% CI 1.09−1.20, p < 0.001, per 1 g/dL decrease), and no statin on discharge (HR 2.13, 95% CI 1.61−2.78, p < 0.001) independently increased long-term mortality. In MI patients, simultaneous diagnosis of an active cancer was associated with less frequently prescribed statins on discharge. Irrespective of cancer diagnosis, no statin use was found as an independent predictor of increased long-term mortality.

Diagnosis and Treatment of Idiopathic Premature Ventricular Contractions: A Stepwise Approach Based on the Site of Origin

Premature ventricular contractions in the absence of structural heart disease are among the most common arrhythmias in clinical practice, with well-defined sites of origin in the right and left ventricle. In this review, starting from the electrocardiographic localization of premature ventricular contractions, we investigated the mechanisms, prevalence in the general population, diagnostic work-up, prognosis and treatment of premature ventricular contractions, according to current scientific evidence.

Prognostic value of statin therapy in patients with myocardial infarction with nonobstructive coronary arteries (MINOCA): a meta-analysis

BACKGROUND

Given the complex aetiology and a limited amount of evidence, the medical treatment (including statin use) of myocardial infarction with non-obstructive coronary artery disease (MINOCA) remains uncertain. The objective of the present study was to evaluate the effect of statin therapy on major cardiovascular events (MACE) and mortality in MINOCA patients.

METHODS

A systematic review and meta-analysis of time-to-event outcomes were performed of studies of statin therapy on MINOCA patients, reporting data from MACE or mortality, after searching the PubMed/MEDLINE, Embase, Science Direct, Scopus, Google Scholar, and Cochrane databases. A fixed-effects meta-analysis model was then applied.

RESULTS

Six observational studies of statin therapy on MINOCA, involving a total of 11,171 patients, were identified and considered eligible for analysis (9129 subjects received statin therapy while 2042 patients were part of the respective control arms). Quantitative analysis (5 studies were included) showed that statin use was associated with lower mortality (HR: 0.65; 95% CI: 0.56-0.75, I²: 0%). Also, the meta-analysis showed that statin therapy was associated with a lower incidence of MACE (HR: 0.78; 95% CI: 0.69-0.88, I²:27%).

CONCLUSION

Our data suggest that in a population with MINOCA, the use of statin therapy results in significant reduction on MACE and mortality. These results must be confirmed in future clinical trials.

Myocardial Inflammation, Sports Practice, and Sudden Cardiac Death: 2021 Update

Myocardial inflammation is an important cause of cardiovascular morbidity and sudden cardiac death in athletes. The relationship between sports practice and myocardial inflammation is complex, and recent data from studies concerning cardiac magnetic resonance imaging and endomyocardial biopsy have substantially added to our understanding of the challenges encountered in the comprehensive care of athletes with myocarditis or inflammatory cardiomyopathy (ICM). In this review, we provide an overview of the current knowledge on the epidemiology, pathophysiology, diagnosis, and treatment of myocarditis, ICM, and myopericarditis/perimyocarditis in athletes, with a special emphasis on arrhythmias, patient-tailored therapies, and sports eligibility issues.