Myocardial Infarction with Nonobstructive Coronary Arteries: The Importance of Achieving Secondary Prevention Targets

Canadian Cardiovascular Society/Canadian Women's Heart Health Alliance Clinical Practice Update on Myocardial Infarction With No Obstructive Coronary Artery Disease (MINOCA)

Myocardial infarction with no obstructive coronary artery disease (MINOCA) represents 6%-15% of all acute coronary syndromes, and women are disproportionately represented. MINOCA is an encompassing preliminary diagnosis, and emerging evidence supports a more expansive comprehensive diagnostic and therapeutic clinical approach. The current clinical practice update summarizes the latest evidence regarding the epidemiology, clinical presentation, and diagnostic evaluation of MINOCA. A cascaded approach to diagnostic workup is outlined for clinicians, for noninvasive and invasive diagnostic pathways, depending on clinical setting and local availability of diagnostic modalities. Evidence concerning the nonpharmacological and pharmacological treatment of MINOCA are presented and summarized according to underlying cause of MINOCA, with practical tips on the basis of expert opinion, outlining a real-life, evidence-based, comprehensive approach to management of this challenging condition.

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.

MINOCA and INOCA: Role in Heart Failure

PURPOSE OF REVIEW

Infarction (MINOCA) and ischaemia (INOCA) with non-obstructive coronary disease are recent non-conventional presentations of coronary syndromes that are increasingly recognised in the clinical arena, particularly with the availability of new cardiovascular imaging techniques. Both are related to heart failure (HF). MINOCA is not associated with benign outcomes, and HF is among the most prevalent events. Regarding INOCA, microvascular dysfunction has also been found to associate with HF, particularly with preserved ejection fraction (HFpEF).

RECENT FINDINGS

Regardless of the several aetiologies underlying HF in MINOCA, it is likely related to LV dysfunction, where secondary prevention is not yet clearly established. Regarding INOCA, coronary microvascular ischaemia has been associated to endothelial dysfunction leading ultimately to diastolic dysfunction and HFpEF. MINOCA and INOCA are clearly related to HF. In both, there is a lack of studies on the identification of the risk factors for HF, diagnostic workup and, importantly, the appropriate primary and secondary prevention strategies.

Myocardial infarction with non-obstructive coronary arteries: Etiology, diagnosis, treatment and prognosis

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is responsible for 10% of myocardial infarctions. Previously, patients were thought to have good prognosis, but evidence-based management and treatment strategies were scarce. Today, researchers and physicians recognize MINOCA as a condition with non-trivial mortality and morbidity. Therapeutic strategies are highly dependent on the underlying disease mechanism in each patient. However, to reach a diagnosis of MINOCA, a multimodal approach is required and, even with an optimal work-up, the cause remains unknown in 8-25% of patients. Research has been growing and position papers from the European Society of Cardiology (ESC) and the American Heart Association/American College of Cardiology have been published, and MINOCA has been included in the more recent ESC guidelines on myocardial infarction. Nonetheless, some clinicians still assume that the absence of coronary obstruction excludes the possibility of acute myocardial infarction. Therefore, in the present paper, we aim to compile and present the available data on the etiology, diagnosis, treatment, and prognosis of MINOCA.

Reducing stress and anxiety in patients with myocardial infarction with non-obstructive coronary arteries or Takotsubo syndrome: A non-randomized feasibility study

BACKGROUND AND AIM

In the aftermath of a myocardial infarction with non-obstructive coronary arteries (MINOCA) or Takotsubo syndrome (TS), patients commonly express high levels of stress and anxiety. Current treatment alternatives rarely address these issues. The planned E-health Treatment of Stress and Anxiety in Stockholm Myocardial Infarction With Non-obstructive Coronaries Study (e-SMINC) aims to evaluate the effects of an internet-based intervention, building on cognitive behavioral therapy (CBT) by comparison with treatment as usual using an RCT approach. This was a small-scale single arm study designed to test the feasibility of the RCT, addressing uncertainties regarding recruitment, data collection, and intervention delivery.

METHODS

Participant recruitment and screening took place before discharge from the coronary care unit at a large Swedish hospital. Eligible patients were invited to a nine-step psychologist guided, internet-based CBT intervention. The sample size was set in advance to 10 participants completing the intervention. The recruitment and flow of participants were documented and evaluated in relation to seven pre-defined progression criteria. Self-reports of anxiety (HADS-A), stress (PSS-14), cardiac anxiety (CAQ), posttraumatic stress (IES-6) and quality of life (Rand-36), collected at screening, pre-intervention and post-intervention, were analysed descriptively and by effect sizes (Cohen's d). Individual interviews targeting participant experiences were conducted.

RESULTS

Six out of seven progression criteria yielded no concerns. Out of 49 patients with a working diagnosis of MINOCA or TS, 31 were eligible for screening, 26 consented to participate, and 14 were eligible with regard to symptoms of stress and/or anxiety. Eleven completed the pre-assessment and were given access the intervention, and 9 completed the intervention. Only the number of patients screened prior to eligibility assessment was slightly lower than expected, indicating possible concerns. Self-reports of anxiety, stress, cardiac anxiety, posttraumatic stress, and quality of life all indicated symptom reduction from pre- to post-intervention, generally showing large effect sizes (d = 0.6-2.6). The general consensus among participants was that the programme was helpful and relevant, and that the personal contact with the psychologist was highly valued. Setting aside time to complete assignments was found critical.

CONCLUSION

Conducting a full scale RCT was found feasible. Inclusion of more study sites and minor amendments to the protocol and intervention were decided to improve feasibility further.

TRIAL REGISTRATION

Clinicaltrials.govNCT04178434.

Myocardial infarction with non-obstructive coronary artery disease

As a result of the increased use of coronary angiography in acute myocardial infarction in the last two decades, myocardial infarction with non-obstructive coronary arteries (MINOCA) has received growing attention in everyday clinical practice. At the same time, research interest in MINOCA has increased significantly. MINOCA is a heterogeneous disease entity seen in 5-10% of all patients with myocardial infarction, especially in women. Clinically, MINOCA may be difficult to distinguish from other non-ischaemic conditions that can cause similar symptoms and myocardial injury. There is still some confusion around the diagnosis, investigation and management of patients with MINOCA. The present review summarises the current knowledge of MINOCA regarding epidemiology, pathophysiology, investigation, and treatment, with a special focus on imaging modalities. In addition, remaining important knowledge gaps are highlighted.

Effectiveness of hospital lipid-lowering protocol of intensive lipid-lowering therapy for patients with acute coronary syndrome

BACKGROUND AND AIMS

The achievement of a target low-density lipoprotein cholesterol (LDL-C) level in clinical settings is often insufficient. A hospital lipid-lowering protocol (HLP) could be effective for providing the optimal lipid-lowering therapy. Herein we determined the effectiveness of a HLP for acute coronary syndrome (ACS) patients.

METHODS

We retrospectively analyzed 1,497 patients who underwent successful percutaneous coronary intervention for ACS at our hospital (November 2011 to May 2020). In December 2018, we introduced a HLP that included the prescription of the maximum tolerated dose of statin, ezetimibe, and eicosapentaenoic acid. We compared the lipid profile and clinical outcomes at 12 months between before (Control group: 1,219 patients) and after the HLP's introduction (HLP group: 278 patients). The primary outcome was the achievement rate of LDL-C < 1.8 mmol/L (70 mg/dL). The key secondary outcomes were the change value and ratio of LDL-C plus the major adverse cardiac events (MACE), defined as a composite of cardiac death, myocardial infarction, target vessel revascularization, and stent thrombosis.

RESULTS

The achievement rate of LDL-C < 1.8 mmol/L was significantly higher in the HLP group than in the Control group (58% vs. 27%, p < 0.01). The HLP group's change ratio and LDL-C values were significantly lower than those of the Control group (-39.5 [-55.1, -13.2]% vs. -20.4 [-38.4, 0]%, p < 0.001; -41 [-69, -11] mg/dL vs. -21 [-38, 0] mg/dL, p < 0.001). MACE was similar between the groups (16.9 vs. 15.5%, p = 0.66).

CONCLUSION

Implementing a HLP for ACS patients improved the achievement of target LDL-C at 12 months.

Adherence to prescription guidelines and achievement of treatment goals among persons with coronary heart disease in Tromsø 7

BACKGROUND

Adherence to clinical practice guidelines for coronary heart disease (CHD) reduces morbidity, mortality and treatment costs. We aimed to describe and compare adherence to prescription guidelines for persons with CHD, and explore its association with treatment goal achievement.

METHOD

We included all participants reporting myocardial infarction, angina, percutaneous coronary intervention and/or coronary artery bypass surgery in the seventh wave of the Tromsø Study (2015-2016, n = 1483). Medication use and treatment goal measures (blood pressure, low-density lipoprotein (LDL)-cholesterol and HbA1c) were compared to clinical practice guidelines on secondary CHD prevention. Propensity score matched logistic regression was used to assess the association between the use of antihypertensive drugs and achievement of treatment goal for blood pressure, and the use of lipid-lowering drugs (LLDs) and achievement of treatment goal for LDL-cholesterol.

RESULTS

The prevalence of pharmacological CHD treatment was 76% for LLDs, 72% for antihypertensive drugs and 66% for acetylsalicylic acid. The blood pressure goal (< 140/90 mmHg, < 140/80 mmHg if diabetic) was achieved by 58% and the LDL-cholesterol goal (< 1.8 mmol/l or < 70 mg/dL) by 9%. There was a strong association between using LLDs and achieving the treatment goal for LDL-cholesterol (OR 14.0, 95% CI 3.6-54.7), but not between using antihypertensive drugs and blood pressure goal achievement (OR 1.4, 95% CI 0.7-2.7).

CONCLUSION

Treatment goal achievement of LDL-cholesterol and blood pressure was low, despite the relatively high use of LLDs and antihypertensive drugs. Further research is needed to find the proper actions to increase achievement of the treatment goals.

Randomized evaluation of beta blocker and ACE-inhibitor/angiotensin receptor blocker treatment in patients with myocardial infarction with non-obstructive coronary arteries (MINOCA-BAT): Rationale and design

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is common and occurs in 6-8% of all patients fulfilling the diagnostic criteria for acute myocardial infarction (AMI). This paper describes the rationale behind the trial 'Randomized Evaluation of Beta Blocker and ACE-Inhibitor/Angiotensin Receptor Blocker Treatment (ACEI/ARB) of MINOCA patients' (MINOCA-BAT) and the need to improve the secondary preventive treatment of MINOCA patients. METHODS: MINOCA-BAT is a registry-based, randomized, parallel, open-label, multicenter trial with 2:2 factorial design. The primary aim is to determine whether oral beta blockade compared with no oral beta blockade, and ACEI/ARB compared with no ACEI/ARB, reduce the composite endpoint of death of any cause, readmission because of AMI, ischemic stroke or heart failure in patients discharged after MINOCA without clinical signs of heart failure and with left ventricular ejection fraction ≥40%. A total of 3500 patients will be randomized into four groups; e.g. ACEI/ARB and beta blocker, beta blocker only, ACEI/ARB only and neither ACEI/ARB nor beta blocker, and followed for a mean of 4 years. SUMMARY: While patients with MINOCA have an increased risk of serious cardiovascular events and death, whether conventional secondary preventive therapies are beneficial has not been assessed in randomized trials. There is a limited basis for guideline recommendations in MINOCA. Furthermore, studies of routine clinical practice suggest that use of secondary prevention therapies in MINOCA varies considerably. Thus results from this trial may influence future treatment strategies and guidelines specific to MINOCA patients.

A Review of the Evidence for Treatment of Myocardial Infarction With Nonobstructive Coronary Arteries

Myocardial infarction (MI) with non-obstructive coronary arteries (MINOCA) is reported in 6% of patients with acute MI referred for catheterization. Because of the complex etiology and a limited amount of evidence, the treatment of MINOCA remains elusive. The etiology of MINOCA manifests from several causes including plaque disruption or erosion, epicardial coronary artery vasospasm, and coronary microvascular dysfunction. In addition, spontaneous coronary artery dissection, takotsubo, and myocarditis have been identified as contributing to the diagnosis of MINOCA. Patients with MINOCA are frequently young, non-white females with fewer traditional risk factors compared with those with an MI caused by obstructive coronary disease. Moreover, women who suffered an MI are 5 times more likely to be diagnosed with MINOCA with a trend for worse outcomes compared with men. The increased recognition/diagnosis of MINOCA has highlighted a gap in our understanding of the treatment of MINOCA. This review identified that there is a paucity of evidence on treatment strategies for patients clinically diagnosed with MINOCA, but more importantly that MINOCA should be viewed as a "syndrome" with many different pathologic causes. This suggests that a standard protocol may not be useful for patients with MINOCA. Given the ongoing debate over the complexity of MINOCA, the main focus in the management of MINOCA should be to identify the underlying mechanism for targeted therapies that may optimize outcomes.

Mechanisms of myocardial infarction with nonobstructive coronary atherosclerosis: a multifaceted play of different actors with guarded prognosis

PURPOSE OF REVIEW

Myocardial infarction (MI) with nonobstructive coronary atherosclerosis (MINOCA) on invasive angiography (stenosis severity <50%) is a heterogenous clinical entity with a prevalence between 6 and 8% of all MI. Whereas the long-term prognosis of MINOCA is not benign, the identification of its underlying mechanism is critical for appropriate risk stratification and tailored secondary prevention strategies.

RECENT FINDINGS

The current review summarizes the contemporary data on the mechanisms, diagnosis, management strategies and outcomes of MINOCA.

SUMMARY

MINOCA is a relatively common form of MI with guarded prognosis. The use of additional diagnostic tests (particularly intracoronary imaging and cardiac magnetic resonance) is paramount to determine the exact cause of MINOCA and implement tailored medical interventions.

Morbidity and cause-specific mortality in first-time myocardial infarction with nonobstructive coronary arteries

BACKGROUND

Myocardial infarction (MI) with nonobstructive coronary arteries (MINOCA) is receiving increasing interest as a prognostically adverse entity distinct from myocardial infarction with significant coronary artery disease (MI-CAD). However, data are still limited regarding long-term cardiovascular morbidity and cause-specific mortality in MINOCA.

METHODS

This is a registry-based cohort study using data from patients admitted to Swedish coronary care units. We investigated various nonfatal outcomes (recurrent MI, hospitalization for heart failure or stroke) and fatal outcomes (cardiovascular, respiratory or cancer-related mortality) in 4069 patients without apparent acute cardiovascular disease, used as non-MI controls, 7266 patients with first-time MINOCA and 69 267 patients with first-time MI-CAD.

RESULTS

Almost all event rates (median follow-up 3.8 years) increased in a stepwise fashion across the three cohorts [rates of major adverse events (MAE; composite of all-cause mortality, recurrent MI, hospitalization for heart failure or stroke): n = 268 (6.6%), n = 1563 (21.5%), n = 17 777 (25.7%), respectively]. Compared to non-MI controls, MINOCA patients had an adjusted hazard ratio (HR) of 2.12 (95% confidence interval 1.84-2.43) regarding MAE. MINOCA patients had a substantial risk of cardiovascular mortality and the highest numerical risks of respiratory and cancer-related mortality. Male sex, previous heart failure and chronic obstructive pulmonary disease had a stronger prognostic impact in MINOCA than in MI-CAD. Female MINOCA patients with atrial fibrillation were at particular risk.

CONCLUSIONS

Patients with first-time MINOCA have a considerable risk of adverse events. This stresses the need for a comprehensive search of the cause of MINOCA, thorough treatment of underlying disease triggers and close follow-up.