It is now very clear that atrial fibrillation (AF) has hit every corner of the globe and is no longer a disorder of the elderly. Over the last two decades, with overwhelming evidence of beneficial outcomes including reduction in mortality, heart failure, and healthcare utilization, catheter ablation of AF has become an established guideline-directed rhythm control treatment [1].

Since the arrhythmogenic foci that initiate AF are clustered at the junction of the pulmonary veins (PVs) and the left atrium (LA), electrical isolation of the PVs (PVI) forms the mainstay of catheter ablation for AF. Patients with persistent and long-standing AF typically have atrial myopathy from widespread fibrosis and scarring. These patients often require focal and linear ablation in the atria besides PVI. In the LA, the mitral valve (MV) isthmus, the left atrial appendage (LAA) isthmus, and the posterior wall of the LA are frequent ablation targets. Being an invasive interventional procedure, catheter ablation of AF also poses significant risks to complications [2]. To minimize complications and improve efficacy, it is paramount that the operators not only are proficient but also have extensive knowledge of the physiology and biophysics of ablation and cardiac anatomy.

In the current issue of the journal, Munawara et al. [3] report on the morphometry of the LA isthmuses (LAA and MV) and anatomical relationships of the coronary vasculatures across the isthmuses. These investigators from India performed meticulous dissection of 15 human cadaveric hearts retrieved from the donated bodies of 9 males and 6 females who had no apparent cardiac illnesses. Specimens with gross abnormality or pathological changes in the LA or the MV were not used for the study. Length of LAA and MV isthmuses and distances between the vessels and the endocardium, myocardium, and perivascular fat thickness along three defined lines were measured. The great cardiac vein (GCV) was found in the lower segment across serial sections from LAA to MV isthmus with a few exceptions of a change of course in both directions of the lower/upper atrial segments observed. The left circumflex artery (LCxA) was consistently located in the lower atrial segments in close proximity of the lower border of the LAA isthmus, at a depth of 2–3 mm within the LAA isthmus, where the myocardial thickness was uniformly 1 mm, the remainder being adipose tissue. In 16% of cases, the LCxA was extremely close (< 1 mm) to the ostium of the left inferior pulmonary vein (LIPV) [3].

Pertaining to the study by Munawara et al. [3], several points are worthy of discussion. For example, how do natural post-mortem changes alter or distort anatomical relationships and morphometric measurements? Given no data on the body mass index, would it be fair to speculate alteration in the vascular course if any in too tall or too short an individual? And, what about any coronary vasculature variants? Would morphometry data from the Indian population be comparable to the ones from other races globally?

Studies involving the Caucasian Polish population by Hołda et al. [4, 5] demonstrated MV isthmus to be significantly longer (28.8 ± 7.0 mm, mean ± standard deviation), almost double in length than the LAA isthmus (14.2 ± 4.8 mm). The distance between the LAA orifice and the LIPV ostium was also longer. Although in the majority of cases the isthmuses were smooth, in 24% of cases of MV isthmus and 4.5% of LAA isthmus, they were abnormal with the presence of crevices, recesses, trabeculations, etc. [4]. The myocardium thickness also varied, being thickest at the LAA end of the LAA isthmus (2.4 ± 0.7 mm) followed by its middle sector (2.1 ± 0.7 mm), and thinnest at the mitral annulus end of the isthmus (1.8 ± 0.6 mm) [5]. As regard coronary vasculature, at least one branch of LCxA was found in 96.5%, and GCV was found in 77.0% of all samples, with interposition of LCxA between the endocardium and GCV in 31.5% of cases, and the smallest distance between the endocardium and LCxA and GCV being 0.5 mm and 0.7 mm, respectively [5]. In an Asian Japanese population study by Eto et al., the shortest distance between the MV annulus and LCxA was at the anterolateral commissure, and the length was 3.3 mm [6].

A more practical question is: how would cadaver dissection data match up with periprocedure multimodality imaging (cardiac CT and MR imaging, angiography, transesophageal and intracardiac echocardiography, and 3-dimensional electroanatomical mapping) data? Cardiac electrophysiologists in the USA and most economically advanced countries rely heavily on such imaging tools in their practices not just for AF ablation but even other complex ablations such as ablation of premature ventricular complexes (PVCs) originating at the coronary cusp, epicardial ventricular tachycardia, para-Hisian foci of arrhythmias, etc. [7, 8]. To appreciate the value of multimodality imaging, we show here an example of ablation of coronary cusp PVC (non-AF arrhythmia) in Fig. 1A–D.

An example of multimodality imaging of coronary cusp premature ventricular contraction (PVC): A coronary angiography at the time of mapping and ablation, location of the ablation catheter at the left coronary cusp in this example; B coronary CT angiography which could be acquired beforehand and integrated with 3-dimensional electroanatomical mapping system; C intraoperative intracardiac echocardiography to visualize cardiac structures in real-time, aortic valve and cusps and adjacent structures with catheter at the commissure between the right and left coronary cusp in this example; and D 3-dimensional electroanatomical mapping, anatomic location of ablation lesions between the right and left coronary cusp to successfully treat PVCs originating at the commissure between the right and left coronary cusp in this example in this example

In a study by Anselmino et al. [9], the investigators used a 3-dimensional electroanatomical mapping CARTO 3 system equipped with an image integration software (CARTOMERGE Plus, Biosense Webster Inc., USA) to merge previously acquired cardiac CT images, thus permitting integration of the 3-dimensional CT reconstruction in the virtual catheter navigation and ablation during AF ablation procedures [9]. By this technique, the median distance between the LCxA and LAA ostium measured 3.0 mm (interquartile range [IQR] 2.1–3.4), and MV annulus measured 3.6 mm (IQR 2.7–6.2), the difference being minimal (≤ 3 mm). Such data further emphasize the value of utilization of sophisticated multi-imaging modalities especially when the ablation strategy incorporates extensive ablation targeting LA isthmuses and the posterior wall of the LA.

On a global scale, however, one needs to be cognizant of the exuberant cost of multimodality imaging unaffordable to a wide group of patients in the developing and poor nations. Furthermore, even possibility of high likelihood of the operators to lack in expertise and familiarity with sophisticated and rapidly evolving technologies exists.

Finally, experiencing the growth of cutting-edge advanced technologies including machine learning and artificial intelligence and their influence on the technology-driven specialty of cardiac electrophysiology on a global stage, one cannot help but wonder whether there has been a parallel growth and advancement in the basic medical faculties such as anatomy. Has anatomy as such changed much? What cadaver dissection has to offer and contribute to the practice of modern contemporary medicine? Reflecting through our own valuable medical training period in the making of physicians at the Seth G S Medical College and KEM Hospital in Mumbai, India, from stepping a foot in the Anatomy Dissection Hall decades ago to practicing in different specialties globally around the world, we concur in our opinion that cadaveric anatomy dissection allows to lay the foundation of perceiving variation as a norm, to appreciate uniqueness in the making of every individual, every system, and every organ in the human body. We hence cannot but commend Munawara and colleagues [3] for their insightful work. Innovative and much-needed studies in basic anatomy such as this one would rejuvenate translational interest to further enhance clinical science globally, beyond the nonpharmacological arena of catheter ablation for cardiac arrhythmias.