Central versus local adjudication of myocardial infarction in a cardiac biomarker trial

Relation of Type 2 Myocardial Infarction and Readmission With Type 1 Myocardial Infarction in Hypertensive Crises (from a Nationwide Analysis)

Type 2 myocardial infarction (T2MI) is an ischemic injury that occurs due to a mismatch between myocardial oxygen supply and demand. T2MI can occur with hypertensive crisis. Nevertheless, the impact of T2MI on hypertensive crisis outcome is poorly understood due to limited data. This study was a retrospective analysis of the National Readmission Database year 2018. Patients were included if the primary diagnosis was hypertensive crisis, hypertensive urgency, or hypertensive emergency. Patients were excluded if they had type 1 myocardial infarction (T1MI), severe sepsis, septic shock, gastrointestinal bleeding, or hemorrhagic anemia at index admission. The primary outcome was 90-day readmission with T1MI. Secondary outcomes were in-hospital mortality, length of stay, resource utilization, and all-cause 90-day readmission. Subgroup analysis was done according to urgency and emergency presentation. A total of 101,211 index hospitalizations were included in our cohort, of whom 3,644 (3.6%) received a diagnosis of T2MI. A total of 912 patients were readmitted within 90 days with T1MI. T2MI was an independent predictor of 90-day readmission with T1MI (adjusted odds ratio [aOR] 2.64, 95% confidence interval [CI] 1.90 to 3.66, p <0.01). Subgroup analysis including only hypertensive urgency and hypertensive emergency yielded similar results (aOR 2.80, 95% CI 1.56 to 5.01, p <0.01 and aOR 2.28, 95% CI 1.59 to 3.27, p <0.01, respectively). In conclusion, T2MI was an independent predictor of poor outcome in patients presenting with hypertensive crisis. Further studies are needed to guide the management of T2MI in this population.

Type 2 Myocardial Infarction: JACC Review Topic of the Week

Acute myocardial infarction (MI) can occur from increased myocardial oxygen demand and/or reduced supply in the absence of acute atherothrombotic plaque disruption; a condition called type 2 myocardial infarction (T2MI). As with any MI subtype, there must be clinical evidence of myocardial ischemia to make the diagnosis. This condition is increasingly diagnosed due to the increasing sensitivity of cardiac troponin assays and is associated with adverse short-term and long-term prognoses. Limited data exist defining optimal management strategies because T2MI is a heterogeneous entity with varying etiologies and triggers. Thus, these patients require individualized care. A major barrier is the absence of a uniform definition that can be operationalized with high reproducibility. This document provides a synthesis of the data about T2MI to assist clinicians' understanding of its pathobiology, when to deploy the diagnosis, and its associated treatments. It also clarifies prognosis, identifies gaps in knowledge, and provides recommendations for moving forward.

Wake Forest University long-term follow-up of type 2 myocardial infarction: The Wake-Up T2MI Registry

Background

The Wake‐Up T2MI Registry is a retrospective cohort study investigating patients with type 2 myocardial infarction (T2MI), acute myocardial injury, and chronic myocardial injury. We aim to explore risk stratification strategies and investigate clinical characteristics, management, and short‐ and long‐term outcomes in this high‐risk, understudied population.

Methods

From 1 January 2009 to 31 December 2010, 2846 patients were identified with T2MI or myocardial injury defined as elevated cardiac troponin I with at least one value above the 99th percentile upper reference limit and coefficient of variation of 10% (>40 ng/L) and meeting our inclusion criteria. Data of at least two serial troponin values will be collected from the electronic health records to differentiate between acute and chronic myocardial injury. The Fourth Universal Definition will be used to classify patients as having (a) T2MI, (b) acute myocardial injury, or (c) chronic myocardial injury during the index hospitalization. Long‐term mortality data will be collected through data linkage with the National Death Index and North Carolina State Vital Statistics.

Results

We have collected data for a total of 2205 patients as of November 2018. The mean age of the population was 65.6 ± 16.9 years, 48% were men, and 64% were white. Common comorbidities included hypertension (71%), hyperlipidemia (35%), and diabetes mellitus (30%). At presentation, 40% were on aspirin, 38% on β‐blockers, and 30% on statins.

Conclusion

Improved characterization and profiling of this cohort may further efforts to identify evidence‐based strategies to improve cardiovascular outcomes among patients with T2MI and myocardial injury.

Long-Term Outcomes in Patients With Type 2 Myocardial Infarction and Myocardial Injury

BACKGROUND

Type 2 myocardial infarction and myocardial injury are common in clinical practice, but long-term consequences are uncertain. We aimed to define long-term outcomes and explore risk stratification in patients with type 2 myocardial infarction and myocardial injury.

METHODS

We identified consecutive patients (n=2122) with elevated cardiac troponin I concentrations (≥0.05 µg/L) at a tertiary cardiac center. All diagnoses were adjudicated as per the universal definition of myocardial infarction. The primary outcome was all-cause death. Secondary outcomes included major adverse cardiovascular events (eg, nonfatal myocardial infarction or cardiovascular death) and noncardiovascular death. To explore competing risks, cause-specific hazard ratios were obtained using Cox regression models.

RESULTS

The adjudicated index diagnosis was type 1 or 2 myocardial infarction or myocardial injury in 1171 (55.2%), 429 (20.2%), and 522 (24.6%) patients, respectively. At 5 years, all-cause death rates were higher in those with type 2 myocardial infarction (62.5%) or myocardial injury (72.4%) compared with type 1 myocardial infarction (36.7%). The majority of excess deaths in those with type 2 myocardial infarction or myocardial injury were because of noncardiovascular causes (hazard ratio, 2.32; 95% confidence interval, 1.92-2.81 versus type 1 myocardial infarction). Despite this finding, the observed crude major adverse cardiovascular event rates were similar between groups (30.6% versus 32.6%), with differences apparent after adjustment for covariates (hazard ratio, 0.82; 95% confidence interval, 0.69-0.96). Coronary heart disease was an independent predictor of major adverse cardiovascular events in those with type 2 myocardial infarction or myocardial injury (hazard ratio, 1.71; 95% confidence interval, 1.31-2.24).

CONCLUSIONS

Despite an excess in noncardiovascular death, patients with type 2 myocardial infarction or myocardial injury have a similar crude rate of major adverse cardiovascular events as those with type 1 myocardial infarction. Identifying underlying coronary heart disease in this vulnerable population may help target therapies that could modify future risk.

Clinical features and outcomes of patients with type 2 myocardial infarction: Insights from the Thrombin Receptor Antagonist for Clinical Event Reduction in Acute Coronary Syndrome (TRACER) trial

BACKGROUND

Type 2 myocardial infarction (MI) is characterized by an imbalance between myocardial blood supply and demand, leading to myocardial ischemia without coronary plaque rupture, but its diagnosis is challenging.

METHODS

In the TRACER trial, patients with non-ST-segment elevation acute coronary syndromes were included. We aimed to describe provoking factors, cardiac biomarker profiles, treatment patterns, and clinical outcomes of patients with type 2 MIs. MI events during trial follow-up were adjudicated by an independent clinical events classification committee (CEC) and were classified according to the Third Universal Definition of MI. Using available source documents retrieved as part of the CEC process, we performed a retrospective chart abstraction to collect details on the type 2 MIs. Cox regression models were used to explore the association between MI type (type 1 or type 2) and cardiovascular death.

RESULTS

Overall, 10.3% (n=1327) of TRACER participants had a total of 1579 adjudicated MIs during a median follow-up of 502 days (25th and 75th percentiles [IQR] 349-667). Of all MIs, 5.2% (n=82) were CEC-adjudicated type 2 MIs, occurring in 76 patients. The incidence of type 2 MI was higher in the first month following randomization, after which the distribution became more scattered. The most frequent potential provoking factors for type 2 MIs were tachyarrhythmias (38.2%), anemia/bleeding (21.1%), hypotension/shock (14.5%), and hypertensive emergencies (11.8%). Overall, 36.3% had a troponin increase >10× the upper limit of normal. Coronary angiography was performed in 22.4% (n=17) of patients during hospitalizations due to type 2 MIs. The hazard of cardiovascular death was numerically higher following type 2 MI (vs. no MI, adj. HR 11.82, 95% CI 5.71-24.46; P<.0001) than that of type 1 MI (vs. no MI, adj. HR 8.90, 95% CI 6.93-11.43; P<.0001).

CONCLUSIONS

Type 2 MIs were more prevalent in the first month after ACS, were characterized by the presence of triggers and infrequent use of an invasive strategy, and were associated with a high risk of death. Further efforts are needed to better define the role and implications of type 2 MI in both clinical practice and research.

Cardiac troponins: 25 years on the stage and still improving their clinical value

Twenty-five years ago, non-isotopic immunoassays for measuring the cardiac specific isoforms of troponin I (cTnI) and T (cTnT) were developed. Both biomarkers radically changed the diagnosis, prognosis, and therapy indication of acute coronary syndromes (ACS) and, particularly, of myocardial infarction (MI). However, cardiac troponins (cTn) rapidly demonstrated their usefulness in other cardiac and non-cardiac conditions, a part of the ischemic coronary diseases. Consequently, the number of patients to be tested for cTn and the number of tests requested to clinical laboratories sharply increased. Though the manufacturers continuously improved the analytical characteristics of the first cTn assays and produced different cTn assay "generations", the universal definition of myocardial infarction required less-than-available analytical imprecision at the cTn concentration used to assess MI (i.e. the 99th reference percentile). To address the clinical requirements, manufacturers developed the high-sensitivity cTn (hs-cTn) assays that allow to measure the 99th reference percentile with adequate precision, to detect cTn in many healthy subjects and, hence, to calculate the hs-cTn biological variation and especially to observe in very short time intervals serial differences in hs-cTn attributable to cardiac ischemia. Since the number of patients attending the emergency departments (ED) for a suspected ACS or MI is increasing, the improved properties of hs-cTn assays, allowing faster and safer patient assessment, will help to alleviate the sometimes overcrowded EDs. However, there are many biological, analytical, and clinical factors that can influence the true hs-cTn values of a patient. Clinicians and laboratory professionals should know about them for the best interpretation of the otherwise largely useful hs-cTn measurements. In conclusion, 25 years after their introduction for clinical use, "cTn are still on the stage and improving their clinical value".

Myocardial Infarction Type 2 and Myocardial Injury

BACKGROUND

The development and implementation of sensitive and high-sensitivity cardiac troponin assays has not only expedited the early ruling in and ruling out of acute myocardial infarction, but has also contributed to the identification of patients at risk for myocardial injury with necrosis, as confirmed by the presence of cardiac troponin concentrations above the 99th percentile. Myocardial injury with necrosis may occur either in the presence of overt ischemia from myocardial infarction, or in the absence of overt ischemia from myocardial injury accompanying other conditions. Myocardial infarction type 2 (T2MI) has been a focus of attention; conceptually T2MI occurs in a clinical setting with overt myocardial ischemia where a condition other than an acute atherothrombotic event is the major contributor to a significant imbalance between myocardial oxygen supply and/or demand. Much debate has surrounded T2MI and its interrelationship with myocardial injury.

CONTENT

We provide a detailed overview of the current concepts and challenges regarding the definition, diagnosis, management, and outcomes of T2MI, as well as the interrelationship to myocardial injury, and emphasize several critical clinical concepts for both clinicians and researchers moving forward.

SUMMARY

T2MI and myocardial injury are frequently encountered in clinical practice and are associated with poor outcomes in both the short term and long term. Diagnostic strategies to facilitate the clinical distinction between ischemic myocardial injury with or without an acute atheroma-thrombotic event vs non–ischemic-mediated myocardial injury conditions are urgently needed, as well as evidence-based therapies tailored toward improving outcomes for patients with T2MI.

Assessment and classification of patients with myocardial injury and infarction in clinical practice

Myocardial injury is common in patients without acute coronary syndrome, and international guidelines recommend patients with myocardial infarction are classified by aetiology. The universal definition differentiates patients with myocardial infarction due to plaque rupture (type 1) from those due to myocardial oxygen supply-demand imbalance (type 2) secondary to other acute illnesses. Patients with myocardial necrosis, but no symptoms or signs of myocardial ischaemia, are classified as acute or chronic myocardial injury. This classification has not been widely adopted in practice, because the diagnostic criteria for type 2 myocardial infarction encompass a wide range of presentations, and the implications of the diagnosis are uncertain. However, both myocardial injury and type 2 myocardial infarction are common, occurring in more than one-third of all hospitalised patients. These patients have poor short-term and long-term outcomes with two-thirds dead in 5 years. The classification of patients with myocardial infarction continues to evolve, and future guidelines are likely to recognise the importance of identifying coronary artery disease in type 2 myocardial infarction. Clinicians should consider whether coronary artery disease has contributed to myocardial injury, as selected patients are likely to benefit from further investigation and in these patients targeted secondary prevention has the potential to improve outcomes.

Type 2 myocardial infarction: the chimaera of cardiology?

The term type 2 myocardial infarction first appeared as part of the universal definition of myocardial infarction. It was introduced to cover a group of patients who had elevation of cardiac troponin but did not meet the traditional criteria for acute myocardial infarction although they were considered to have an underlying ischaemic aetiology for the myocardial damage observed. Since first inception, the term type 2 myocardial infarction has always been vague. Although attempts have been made to produce a systematic definition of what constitutes a type 2 myocardial infarction, it has been more often characterised by what it is not rather than what it is. Clinical studies that have used type 2 myocardial infarction as a diagnostic criterion have produced disparate incidence figures. The range of associated clinical conditions differs from study to study. Additionally, there are no agreed or evidence-based treatment strategies for type 2 myocardial infarction. The authors believe that the term type 2 myocardial infarction is confusing and not evidence-based. They consider that there is good reason to stop using this term and consider instead the concept of secondary myocardial injury that relates to the underlying pathophysiology of the primary clinical condition.

Supply/demand type 2 myocardial infarction: should we be paying more attention?

Supply/demand (type 2) myocardial infarction is a commonly encountered clinical challenge. It is anticipated that it will be detected more frequently once high-sensitivity cardiac troponin assays are approved for clinical use in the United States. We provide a perspective that is based on available data regarding the definition, epidemiology, etiology, pathophysiology, prognosis, management, and controversies regarding type 2 myocardial infarction. Understanding these basic concepts will facilitate the diagnosis and treatment of these patients as well as ongoing research efforts.