Abstract
The great majority of patients presenting to the emergency department with recent onset chest pain without ST segment elevation do not have an acute coronary syndrome (ACS).1,2 Therefore, it is important to have diagnostic algorithms and risk stratification tools that allow accurate and quick diagnosis of an ACS but also identification of very low risk chest pain patients that safely can be discharged without hospitalisation. As more than one third of the patients with recent onset chest pain have a very low risk of major adverse cardiac events it would very useful to have risk stratification tools that allow to identify these patients before transportation to the hospital is considered. The HEART score that is based on the patients’ history, ECG changes, age, cardiovascular risk factors and a measurement of cardiac troponin has been developed to risk stratify undifferentiated chest pain patients in the emergency department. In a first study of the FamouS Triage project the feasibility of using a modified HEART score at the patient’s home, incorporating only a single highly sensitive troponin T (hs cTn T) measurement was assessed. 3 Although false negative hs cTn T test results were observed in almost one in three patients the study shows that the use of a modified HEART score allows to reliably identify chest pain patients with a low probability of having an ACS what may lead to a reduction of overcrowding at the emergency department, healthcare costs and unnecessary patient anxiety.
The HEART score is however not 100% fool proof in identifying low risk chest pain patients who may be considered for early discharge from the emergency department: in a meta-analysis of nine studies including data from 11,217 patients still 3.3% of the patients with a HEART score 0 to 3 developed a major adverse cardiac event (MACE). 4 Although the HEART score was designed to be used with any commercially available troponin assay its diagnostic sensitivity maybe lower when high sensitivity assays are used and therefore further validation of the HEART score in combination with these assays will be needed.
The increased analytical sensitivity of contemporary hs cTn assays has improved considerably the diagnostic accuracy and speed of both ruling out and ruling in acute myocardial infarction (MI) in patients presenting with symptoms suggestive of an ACS. This evolution has resulted in the reclassification of many patients who previously were diagnosed as unstable angina into non ST segment elevation MI (NSTEMI) what has led to the suggestion that the requiem for the diagnosis of unstable angina should be prepared. 5 The detection of elevated hs cTn values above the 99th percentile in a significant proportion of patients without acute coronary events (chronic myocardial injury) challenges again the classification but also our understanding of the pathophysiology of the various ischemic heart syndromes. In this issue, the current challenges in the diagnosis of unstable angina when using high-sensitivity cardiac troponin assays are reviewed and a new classification of unstable angina is proposed. 6
The ESC guidelines for the management of ACS in patients presenting without persistent ST-segment elevation (NSTEACS) recommend to use the Global Registry of Acute Coronary Events (GRACE) score for risk stratification of patients with a suspected ACS 1 Use of additional biomarkers may improve the risk stratification beyond the GRACE score as demonstrated by a prospective real-world multicentre registry of ACS patients performed in Switzerland: the addition of hs cTn T, N-terminal-pro B-type natriuretic peptide (NT-proBNP) and high sensitivity C-reactive protein (hsCRP) improved the risk discrimination for all-cause mortality and the composite endpoint of all-cause mortality or recurrent MI during short and long-term follow-up. 7 Furthermore, the combination of the GRACE score and NT-proBNP was a better predictor of new-onset acute heart failure during 1 year follow-up than the GRACE score alone.
Early and accurate diagnosis of acute MI is crucial to successful treatment and improved outcomes. There appears to be a major deficit in accuracy in the initial diagnosis of acute MI as demonstrated by an analysis performed on a very large cohort of patients discharged with a final diagnosis of ST-elevation MI and NSTEMI from the nation-wide Myocardial Ischaemia National Audit Project (MINAP). 8 Almost one in three patients with acute MI had other diagnoses at first medical contact and received less frequently guideline indicated care what resulted in significantly higher mortality rates. This study illustrates that there is a substantial potential, greater for NSTEMI than STEMI, to improve outcomes through earlier and more accurate diagnosis of acute MI.
Heart rate is a vital parameter that is measured immediately on hospital admission in every cardiac patient. Previously it was already shown that heart rate on admission in ACS patients is a predictor of in hospital mortality and also provides prognostic information on the clinical outcome after hospital discharge. Analysis of a large contemporary dataset of ACS patients admitted to 58 hospitals from 6 participant countries of the European Hospital Benchmarking by Outcomes in ACS Processes (EURHOBOP) collaboration showed a U-shaped relationship between admission heart rate and in-hospital mortality both in STEMI and NSTEACS patients. 9 Both a high (>80 bpm) as a well a low heart rate (<50 to 60 bpm) was associated with an increased mortality. Patients with a marked bradycardia on admission (<40 bpm) had the highest risk and may represent a ‘ pre-cardiogenic shock’ subgroup that presented with lower blood pressure, haemoglobin and worse kidney function at admission.
Periprocedural MI has been consistently associated with increased mortality in ACS patients undergoing coronary revascularization. With the shortening of treatment intervals of both pharmacological and interventional therapies in ACS patients the assessment and distinction of periprocedural and early recurrent MI is difficult and represents a need if innovative early treatments have to be evaluated. A post hoc analysis of 3 large clinical trials (CHAMPION PCI, CHAMPION PLATFORM, and CHAMPION PHOENIX) comparing cangrelor with either clopidogrel or placebo in patients undergoing percutaneous coronary intervention (PCI) showed that the adoption of more stringent criteria for the diagnosis to diagnose PCI-related MI the assessment of baseline status and PCI-related MI in patients with ACS, integrating multiple biomarker assessments ischemic symptoms, and ECG changes, was associated with markedly lower event rates as compared with prior definitions, and also enhanced the ability to detect a treatment effect. 10 This illustrates the major implications of more rigorously defined endpoint criteria on clinical trial results and emphasizes the importance of a meticulous assessment of PCI-related MI in ACS patients.
Although modern cardiology has reduced considerably both mortality and morbidity of ischemic heart disease during the last 50 years, 11 the aging of the population during the next decades 12 will bring a dramatic rise in absolute numbers of hospital admissions of mostly elderly patients with a suspected ACS. A structured review in this issue found that nearly a third of older people presenting to the hospital with ACS are frail or pre-frail. 13 These patients are less likely to receive lifesaving early invasive treatment under the protection of modern potent antithrombotic therapy and are therefore at much higher risk of dying from a complication following hospitalisation for ACS.
Frailty of the patients should be more frequently considered in the management of acute cardiovascular diseases as the prevalence of elderly people is progressively increasing. A position paper from the Acute Cardiovascular Care Association presents the latest evidence about frailty and the management of frail patients with acute cardiovascular diseases and provides possible avenues for future research. 14