Effect of Secondary Prevention Medication on the Prognosis in Patients With Myocardial Infarction With Nonobstructive Coronary Artery Disease

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.

Diagnostic Puzzles and Cause-Targeted Treatment Strategies in Myocardial Infarction with Non-Obstructive Coronary Arteries: An Updated Review

Myocardial infarction with nonobstructive coronary arteries (MINOCA) is a distinct subtype of myocardial infarction (MI), occurring in about 8-10% of spontaneous MI cases referred for coronary angiography. Unlike MI with obstructive coronary artery disease, MINOCA's pathogenesis is more intricate and heterogeneous, involving mechanisms such as coronary thromboembolism, coronary vasospasm, microvascular dysfunction, dissection, or plaque rupture. Diagnosing MINOCA presents challenges and includes invasive and non-invasive strategies aiming to differentiate it from alternative diagnoses and confirm the criteria of elevated cardiac biomarkers, non-obstructive coronary arteries, and the absence of alternate explanations for the acute presentation. Tailored management strategies for MINOCA hinge on identifying the underlying cause of the infarction, necessitating systematic diagnostic approaches. Furthermore, determining the optimal post-MINOCA medication regimen remains uncertain. This review aims to comprehensively address the current state of knowledge, encompassing diagnostic and therapeutic approaches, in the context of MINOCA while also highlighting the evolving landscape and future directions for advancing our understanding and management of this intricate myocardial infarction subtype.

Dual Antiplatelet Therapy: A Concise Review for Clinicians

Dual antiplatelet therapy (DAPT) combines two antiplatelet agents to decrease the risk of thrombotic complications associated with atherosclerotic cardiovascular diseases. Emerging data about the duration of DAPT is being published continuously. New approaches are trying to balance the time, benefits, and risks for patients taking DAPT for established cardiovascular diseases. Short-term dual DAPT of 3-6 months, or even 1 month in high-bleeding risk patients, is equivalent in terms of efficacy and effectiveness compared to long-term DAPT for patients who experienced percutaneous coronary intervention in an acute coronary syndrome setting. Prolonged DAPT beyond 12 months reduces stent thrombosis, major adverse cardiovascular events, and myocardial infarction rates but increases bleeding risk. Extended DAPT does not significantly benefit stable coronary artery disease patients in reducing stroke, myocardial infarction, or cardiovascular death. Ticagrelor and aspirin reduce cardiovascular events in stable coronary artery disease with diabetes but carry a higher bleeding risk. Antiplatelet therapy duration in atrial fibrillation patients after percutaneous coronary intervention depends on individual characteristics and bleeding risk. Antiplatelet therapy is crucial for post-coronary artery bypass graft and transcatheter aortic valve implantation; Aspirin (ASA) monotherapy is preferred. Antiplatelet therapy duration in peripheral artery disease depends on the scenario. Adding vorapaxar and cilostazol may benefit secondary prevention and claudication, respectively. Carotid artery disease patients with transient ischemic attack or stroke benefit from antiplatelet therapy and combining ASA and clopidogrel is more effective than ASA alone. The optimal duration of DAPT after carotid artery stenting is uncertain. Resistance to ASA and clopidogrel poses an incremental risk of deleterious cardiovascular events and stroke. The selection and duration of antiplatelet therapy in patients with cardiovascular disease requires careful consideration of both efficacy and safety outcomes. The use of combination therapies may provide added benefits but should be weighed against the risk of bleeding. Further research and clinical trials are needed to optimize antiplatelet treatment in different patient populations and clinical scenarios.

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 nonobstructive coronary arteries: from pathophysiology to therapeutic strategies

Myocardial infarction with nonobstructive coronary arteries (MINOCA) is a heterogeneous group of clinical entities characterized by clinical evidence of acute myocardial infarction (AMI) with normal or near-normal coronary arteries on coronary angiography (stenosis < 50%) and without an over the alternative diagnosis for the acute presentation. Its prevalence ranges from 6% to 11% among all patients with AMI, with a predominance of young, nonwhite females with fewer traditional risks than those with an obstructive coronary artery disease (MI-CAD). MINOCA can be due to either epicardial causes such as rupture or fissuring of unstable nonobstructive atherosclerotic plaque, coronary artery spasm, spontaneous coronary dissection and cardioembolism in-situ or microvascular causes. Besides, also type-2 AMI due to supply-demand mismatch and Takotsubo syndrome must be considered as a possible MINOCA cause. Because of the complex etiology and a limited amount of evidence, there is still some confusion around the management and treatment of these patients. Therefore, the key focus of this condition is to identify the underlying individual mechanisms to achieve patient-specific treatments. Clinical history, electrocardiogram, echocardiography, and coronary angiography represent the first-level diagnostic investigations, but coronary imaging with intravascular ultrasound and optical coherent tomography, coronary physiology testing, and cardiac magnetic resonance imaging offer additional information to understand the underlying cause of MINOCA. Although the prognosis is slightly better compared with MI-CAD patients, MINOCA is not always benign and depends on the etiopathology. This review analyzes all possible pathophysiological mechanisms that could lead to MINOCA and provides the most specific and appropriate therapeutic approach in each scenario.

Myocardial Infarction with Nonobstructive Coronary Arteries

Myocardial infarction with nonobstructive coronary arteries (MINOCA) is an important subtype of myocardial infarction (MI) that occurs in approximately 6-8% of patients with spontaneous MI who are referred for coronary angiography. MINOCA disproportionately affects women, but men are also affected. Pathogenesis is more variable than in MI with obstructive coronary artery disease (MI-CAD). Dominant mechanisms include atherosclerosis, thrombosis, and coronary artery spasm. Management of MINOCA varies based on the underlying mechanism of infarction. Therefore, systematic approaches to diagnosis are recommended. The combination of invasive coronary angiography, multivessel intracoronary imaging, provocative testing for coronary spasm, and cardiac magnetic resonance imaging provides the greatest diagnostic yield. Current clinical practice guidelines for the secondary prevention of MI are based largely on data from patients with MI-CAD. Thus, optimal medications after MINOCA are uncertain. Clinical trials focused on the treatment of patients with MINOCA are urgently needed to define optimal care.

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.

Prognostic impact of secondary prevention medical therapy following myocardial infarction with non-obstructive coronary arteries: a Bayesian and frequentist meta-analysis

AIMS

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a clinical entity with several causes and pathophysiologic mechanisms. Secondary prevention with medical therapy used in patients with obstructive coronary artery disease has unclear benefits in MINOCA patients.

METHODS AND RESULTS

A literature search was conducted until 8 March 2022. Random-effect frequentist and hierarchical Bayesian meta-analyses were performed to assess the clinical impact of medical therapy [renin-angiotensin-aldosterone system (RAAS) inhibitors, statins, dual antiplatelet therapy (DAPT), β-blockers] in MINOCA patients. Outcomes of interest were all-cause mortality and major adverse cardiovascular events (MACE). A total of 12 663 MINOCA patients among five observational studies were analysed. The mean follow-up ranged from 12 to 90 months across studies. In frequentist meta-analysis, statins and β-blockers were associated with a lower risk of all-cause mortality [pooled adjusted hazard ratios (aHRs) 0.53 and 0.81, with 95% confidence intervals (CIs) (0.37-0.76) and (0.67-0.97), respectively]. Only RAAS inhibitors were associated with a lower risk of MACE [pooled aHR: 0.69, with 95% CI (0.53-0.90)]. Bayesian meta-analysis based on informative prior assumptions offered strong evidence only for the benefit of statins on decreasing the risk of all-cause death [Bayes factor (BF): 33.2] and moderate evidence for the benefit of RAAS inhibitors on decreasing the risk of MACE (BF: 9); assigning less informative prior distributions did not affect the results, yet it downgraded the level of evidence to anecdotal.

CONCLUSION

In this meta-analysis, statins and RAAS inhibitors were consistently associated with a lower risk of all-cause mortality and MACE, respectively, in patients with MINOCA. Neutral prognostic evidence was demonstrated for β-blockers and DAPT.

Impact of secondary prevention medical therapies on outcomes of patients suffering from Myocardial Infarction with NonObstructive Coronary Artery disease (MINOCA): A meta-analysis

AIMS

To assess the impact of secondary prevention medical therapies (statins, ACE-inhibitors/Angiotensin Receptor Blockers (ARB), beta-blockers (BB) and Dual Antiplatelet Therapy (DAPT)) on outcomes of patients with myocardial infarction with nonobstructive coronary artery disease (MINOCA).

METHODS

Five adjusted observational studies encompassing 10,546 were included in this meta-analysis. All-cause death was the primary endpoint, while Major Adverse Cardiovascular Events (MACE) and acute myocardial infarction (AMI) were the secondary endpoints.

RESULTS

After 24 months of follow up, statins (tested in 8093 patients) were associated with a reduced risk of all-cause death (HR 0.60:0.45-0.81, p 〈0,001), while ACE-inhibitors/ARB (on 9666 patients) were not. Aggregate data from two studies (n = 9720, 7719 on beta-blockers, 6423 on DAPT) indicated that beta-blockers and DAPT (median follow-up 34.1 and 15.7 months, respectively) were both associated with a significant reduction of all-cause death (HR0.81:0.66-0.99, p = 0.04, and HR0.73:0.55-0.98, p = 0.03, for beta-blockers and DAPT, respectively). Among the investigated therapies, only ACE-inhibitors/ARBs entailed a reduced risk of MACE (HR0.65:0.44-0.94, p = 0.02, all CI 95%) over 36.5 months (four studies, n = 10,150). None of the investigated therapies was associated with a reduced risk of AMI.

CONCLUSIONS

Data from adjusted observational studies suggest that beta-blockers, statins and DAPT are associated with a survival benefit among MINOCA patients. ACE-inhibitors/ARB entail a reduced risk of MACE while none of the investigated secondary prevention therapies is associated with a reduced risk of AMI. Randomized controlled trials are warranted to confirm these findings.

The Role of Antiplatelet Therapy in Patients With MINOCA

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a heterogeneous group of clinical entities characterized by the common clinical evidence of myocardial infarction (MI) with non-obstructive coronary arteries on coronary angiography and without an overt cause for the MI. Platelets play a cornerstone role in the pathophysiology of MI with obstructive coronary arteries. Accordingly, antiplatelet therapy is recommended for treating patients with MI and obstructive coronary disease. However, the role of platelets in the pathophysiology of MINOCA patients is not fully defined, questioning the role of antiplatelet therapy in this setting. In this review, we will assess the role of antiplatelet therapy in MINOCA with a focus on the pathophysiology, therapeutic targets, current evidence, and future directions according to its different etiologies.

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.

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.