Gherardo Finocchiaro, MD Consultant Cardiologist, Inherited Cardiac Conditions, Cardiac Imaging, Sports Cardiology at St George's University Hospitals NHS Foundation Trust speaks about The Labyrinth Of Nomenclature In Cardiology. Eternal Dilemmas And New Challenges On The Horizon In The Personalized Medicine Era.
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The search for precise terminology and classifications is a continual source of conundrums in medicine and research, and it's especially relevant and contentious in the field of cardiovascular disorders.
The cardiology community is split between customized medicine and imprecise diagnostic categories, which are frequently used to describe non-entities. The exponential expansion in information, which coincides with a continual rise in complexity, has sparked a dispute about the appropriate classifications. The need to capture each individual's fundamental physiological or pathological characteristics may conflict with the need to categorize, as no categorization can fully portray the complexity of reality.
We will explore how terminology and classifications in the field of cardiovascular illnesses originated, as well as the key nomenclature deadlocks, in this perspective. We'll start with the philosophical foundations of this long-running argument before moving on to practical issues, using the topic of cardiomyopathies and heart failure as an illustration (HF).
Classifications and terminologies A lengthy trip through philosophy
The terminology refers to the verbal labels that are linked to an idea, and it has long been a source of conundrums in philosophy, science, and, of course, medicine. Terminology and classifications have been a source of contention since at least the fifth century BC. 1 Plato devotes a large section of his dialogues to the so-called "theory of forms" or "theory of ideas," in which he attempts to answer the central question "What is the essence of things?" He believed that the object was fundamentally the shape and that the phenomena (v: to emerge) were shadows of the form [the difference between essence and phenomena is powerfully depicted in Plato's Republic allegory of the cave].
Aristotle had a more empirical approach to reality. He proposed that abstract ideas are descriptions of objects that have been categorized based on their characteristics. He proposes the concept of characteristics as categories. This perspective rejects Platonic extreme realism in favor of a view of the universal as a characteristic within a thing and everything else that is unique to it. A substance's essence is its substantial form, and as only universals can be defined, substantial forms are universals.
Several philosophers and theologians of the Middle Ages (William of Ockam, Roscellinus, and others) rejected realistic ideas in favor of nominalism. While Plato (and Platonists) believed that distinct objects are the way they are because of the presence of a universal, nominalism holds that only particulars exist and that they are derived from our representational system or language (the way we speak of the world). Human conventions tend to classify objects or ideas into categories that exist because we choose to name them rather than because they are universal abstractions.
Immanuel Kant, more recently, proposed that universals are not actual, but rather concepts in rational persons' minds, basic categories of pure reason organically related to the rationality of the individual making the judgment. Ludwig Wittgenstein, a twentieth-century philosopher, focused his work primarily on the relationship between language and reality, acknowledging the great limitations of terminology, which is highly context-dependent and assumes a private meaning that is understood differently by individuals participating in a conversation.
Modern taxonomy was originally created in the 16th and 17th centuries, long before the 20th-century era of clinical descriptions, such as Standardized Nomenclature of Diseases (SND) and International Classification of Diseases (ICDS) (ICD).
Cardiomyopathies are an example of this.
In an attempt to capture the complex character of cardiomyopathies, several definitions and categories have been proposed. The European Society of Cardiology (ESC) offers a categorization based on a phenotypic expression that supports an empiric approach.
These categories reflect commendable attempts that will undoubtedly give some clarity in the area. Classifications make use of categories and names that should capture the many manifestations of a cardiac ailment while also capturing the core of the disease. This assumption's inherent failure can be described in a variety of ways. The term "hypertrophic cardiomyopathy" (HCM) refers to a pathological condition characterized by cardiac hypertrophy. We're seeing more and more cases where there are signs and symptoms of HCM, such as lateral deep T-wave inversion or a family history of HCM, yet the wall thickness at the left ventricular apex is just 11 or 12 mm (not surpassing the international criterion of 15 mm). We would undoubtedly be reluctant to label the aforementioned ailment HCM if we strictly read rules and the importance of the term. Similar difficulties arise when interpreting post-mortem cardiac findings in decedents of sudden death with (or without) hypertrophy: Some researchers believe that HCM can be diagnosed without hypertrophy but with significant myocardial disarray (a profound derangement of normal myocyte alignment on histology); on the other hand, unexplained hypertrophy in the setting of sudden death should not be considered part of the HCM disease spectrum.
Other cardiomyopathies are in the same boat. The term "arrhythmogenic right ventricular cardiomyopathy" conjures up images of a disease marked by arrhythmias and affecting the right ventricle. Longitudinal investigations have revealed that, while a large number of individuals suffer from arrhythmias, many of them have a fairly steady trajectory. Furthermore, it appears that blaming simply the right ventricle is insufficient, as the left ventricle has lately been found to be damaged as well (or maybe the only chamber affected).
A phenotypic categorization (or nomenclature) has the inherent danger of halting the diagnostic process at first sight and incorrectly classifying a morphologic feature as a particular illness.
Heart failure is one example.
Because HF is a condition rather than a disease, a certain level of nomenclature complexity is usually unavoidable. HF with decreased ejection fraction (HFrEF), HF with mid-range ejection fraction (HFmrEF), and HF with preserved ejection fraction (HFpEF) are the three categories defined by the ESC recommendations based on left ventricular ejection fraction (HFpEF). This categorization is clear, although it does have some limits. The ejection fraction can not distinguish between aetiologies, thus a patient with a low left ventricular ejection fraction might have ischemic heart disease or hereditary dilated cardiomyopathy.
Even greater causal variability may be seen in the HFpEF group, which could be termed a "nosographic trap." Many randomized clinical trials in people with HFrEF have yielded significant results. The same cannot be true for HFpEF sufferers. Although the causes for this discrepancy are unknown, the nosographic instability that characterizes this condition might be a major factor in clinical trial failure in HFpEF. Indeed, HFpEF is a depiction of a 'non-thing,' not a description of clinical reality. The term 'HFpEF' has the potential to be too broad, including a wide range of clinical entities, each needing unique therapy. This language impasse may be to blame for the failure of clinical trials evaluating the efficacy of various medicines in HFpEF.
Differential diagnosis is a problem.
Differential diagnosis is difficult in the field of HF and cardiomyopathies since distinct disease entities can have the same phenotype and a single illness might have multiple phenotypes. A growing number of research are attempting to evaluate and compare certain characteristics in order to show that they are useful in distinguishing A from B. This experimental method, on the other hand, is based on a dichotomous and mutually exclusive interpretation of reality, and hence assumes that A and B are distinct things. Nature, on the other hand, seldom follows binary laws. The challenge of differential diagnosis between physiological adaptation to exercise and cardiomyopathies is an example. We must acknowledge that an athlete may have cardiomyopathy, and that a patient with cardiomyopathy can be an athlete, and that the phenotypic is a mix of physiological and pathological processes (Figure 2). For instance, the assumption that A and B (for example, dilated cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy) are two distinct clinical entities is a postulate: A and B are distinct because we arbitrarily and customarily choose to designate them by different names (following the aforementioned nominalist vision).
Differential diagnosis of athlete's heart and dilated cardiomyopathy (DCM) using a dichotomous approach (A). Because it is possible to combine DCM and physiological adaptation to exercise, a strategy focused on the awareness of "shades of grey" rather than a mutually exclusive interpretation of clinical data would accommodate for the limitations of our knowledge based on empiric reality (phenotype) (B). LBBB, left bundle branch block; LV, left ventricle; LVEF, left ventricular ejection fraction; LVH, left ventricular hypertrophy; ECG, electrocardiogram; FH, family history; LBBB, left bundle branch block; LV, left ventricle; LVEF, left ventricular ejection fraction; LVH, left ventricular hypertrophy; LVH, left ventricular hypertrophy; LVH, left ventricular hypert RV, right ventricle; RVH, right ventricular hypertrophy; MRI, magnetic resonance imaging SCD is for sudden cardiac death; TWI stands for T-wave inversion; and VO2 stands for oxygen consumption.