Author: CSANZ Admin

Stem: A 29 year-old male presents with a 2 month history of frequent palpitations. His initial ECG is shown in Figure A. Bedside TTE shows mild-moderate global LV dysfunction. What are the differential diagnoses?

Answer: This is a regular wide complex tachycardia with left bundle branch block morphology (QRS width ~ 125ms). Differential diagnoses for regular wide complex tachycardia (QRS > 120 ms) in general include VT, SVT with aberrancy (any regular SVT – inc. atrial tachycardia, AVNRT, AVRT, atrial flutter, sinus tachycardia), and pre-excited tachycardia. The typical LBBB morphology suggests that the ventricle is being activated from the region of the right bundle. Hence, specific diagnoses to consider given the morphology include SVT with LBBB aberrancy (or fixed LBBB), bundle branch reentrant VT, idiopathic moderator band VT and atriofascicular antidromic tachycardia.

Stem (continued): Adenosine was given with no effect suggesting this was less likely to be a re-entrant SVT involving the AV node (ie. AVNRT, AVRT). He was subsequently given metoprolol and amiodarone – ECGs post are shown (Figure B and C). Does this help with the diagnosis?

Answer: These ECGs rule in VT – there is clear cut AV dissociation (sinus p waves regularly marching through). In Figure C, there is some irregularity suggesting an automatic (rather than re-entrant) mechanism. VT continued despite cardioversion and amiodarone. Thus the patient has incessant VT causing a tachycardia mediated cardiomyopathy. Catheter ablation was performed with the focal VT successfully ablated at the moderator band (adjacent to the exit of the right bundle – hence the typical LBBB morphology). LV function returned to normal after 2 months.

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Prof Kazuaki Negishi, 24 May 2022

Cardio-oncology is a rapidly emerging speciality globally. Cardio-oncology is dedicated to the prevention, identification, and treatment of cardiovascular complications in cancer patients as well as in long-term survivors. This is pertinent as cancer treatments are more complex than ever and cancer survivorship is rapidly increasing. Notably, Australia has one of the best cancer survivor rates globally.

An article published in the Internal Medicine Journal, led by Professor Kazuaki Negishi, senior author and of University of Sydney and Nepean Hospital assessed the status of cardio-oncology services in Australia through an online multi-disciplinary survey. There were 118 responses analysed with 70% reporting no dedicated cardio-oncology services existed at their institution, with insufficient funding being the main reason. Most respondents were oncologists (35%), followed by cardiologist (31%), haematologist (18%) and radiation oncologists (14%). The vast majority of respondents agreed or strongly agreed (86%) cardio-oncology is an important sub-speciality. Cancer specialists estimated 15% of their patients did not receive optimal cancer care due to cardiotoxicity or a history of cardiovascular disease. Additionally, 50% of cancer specialists were neutral to very unconfident in identifying cardiotoxicity. In regard to cardio-oncology education, nearly all respondent supported increased cardio-oncology session at national society meetings (88%) and the creation of national cardio-oncology guidelines (97%).

The results of this Australian first survey demonstrate “the overwhelming support for Australian cardio-oncology guidelines and an increased presence at national society meetings suggest there is a sizable appetite for the growth of cardio-oncology services in Australia.” Hopefully, these findings can be used for an evidence base for further funding of cardio-oncology services in Australia.

In conclusion, the authors suggest “a multi-disciplinary team funding model following existing templates in oncology may be a pathway forward. Our findings indicate that there is a strong support for further cardio-oncology education, guidelines and services nationally.”

You can find the full article here: https://onlinelibrary.wiley.com/doi/10.1111/imj.15682

A 25 year-old male with no past history presents with palpitations.

What is the most likely diagnosis?    Why are there two QRS morphologies?

The Answer:

This is a ‘regularly irregular’ narrow complex tachycardia (hence not AF). There are clear p-waves marching through (with more A’s than V’s) with an isoelectric interval between them suggestive of a focal atrial tachycardia (blue arrow), particularly in the absence of structural heart disease. The p waves are inferiorly directed, suggesting they are coming from the top of the atria. In this case, there is Wenckebach conduction down the AV node (3:2 ratio) with progressive PR prolongation before a dropped beat. The change in QRS morphology is due to Ashman phenomenon – this is aberrant ventricular conduction affecting the distal conduction system due to a change in QRS cycle length, and it can be seen in any supraventricular arrhythmia. It is usually described as a wide QRS complex that follows a short R-R interval preceded by a long R-R interval (L – long, S – short in Figure).  I occurs because the action potential duration (and hence refractory period) changes with the preceding R–R interval. A longer cycle lengthens the ensuing refractory period, and if a shorter cycle follows, the beat terminating the cycle tends to be conducted with aberrancy. The patient underwent catheter ablation of a focal tachycardia arising near the crista terminalis / SVC region.

Summary by Paul Bridgman

Louise Cullen et al; Heart, Lung and Circulation  

Cullen and colleagues have previously reported that the IMPACT (The Improved Assessment of Chest Pain Trial) protocol can safely and efficiently allow a large proportion of general patients presenting to EDs with chest pain to undergo accelerated assessment for low, intermediate or high risk of an acute coronary syndrome (ACS).¹ After risk assessment, and 2-hour serial troponin results, those deemed at low-risk could be safely discharged without further objective assessment.
Now, working with support from local Aboriginal and Torres Strait Islander Health Community-Controlled Health Organisations (ATSICCHOs), Cullen and colleagues have confirmed that the IMPACT pathway can also be safely implemented for patients of Aboriginal and Torres Strait Islander origin.²
In this trial, high and intermediate risk was managed according to the IMPACT pathway, but low-risk patients had additional cardiac testing in line with the National Heart Foundation/Cardiac Society of Australia and New Zealand 2016 guidelines for the management of ACS.³
Conducted in the Emergency Department of Cairns Hospital, Queensland between November 2017 and December 2019, the trial recruited 155 patients, classified as 11.6% low-risk, 56.1% intermediate-risk and 32.3% high risk for ACS. All patients with ACS were identified on their index admission. None of the patients assessed as low risk of ACS had any evidence of coronary artery disease from objective testing, and none had adverse cardiac events within 30 days of presentation. However, a high burden of cardiovascular risk factors was noted in this cohort.

The research found higher rates of ACS and at a younger age compared with the first IMPACT trial. It also found a high proportion of females with ACS (male, 38.1%). The authors state these findings should not only inform clinicians but also direct public health campaigns to better target those at risk.

You can find the full article here: https://www.heartlungcirc.org/article/S1443-9506(22)00078-6/fulltext  

1. Med J Aust 2017; 207 (5): 195-200.
2. Heart Lung Circ 2022; DOI:  https://doi.org/10.1016/j.hlc.2022.02.010
3. Heart Lung Circ 2016; 25:895-951.

A randomised controlled trial of stress in stress cardiomyopathy patients

By Paul Bridgman 23 March 2022

It has been long debated whether the cause for stress cardiomyopathy is in the brain, the heart, or even perhaps in the connection between the two. A cardinal feature of the cardiomyopathy is QT prolongation, onset shortly after the precipitating event and then worsening over an average of three days before resolving.  Published this week in PLOS One, a randomised control trial seeks to establish whether women who have recovered from stress cardiomyopathy show any increased susceptibility to QT prolongation with repeated exposure to emotional stress.

The trial included 12 women with a history of the condition and 12 controls without major cardiovascular disease. On two separate occasions, these women had 24-hour ECGs recorded with a holter monitor and were either subjected to a stress-inducing hyperventilation exercise or a calming diaphragmatic breathing exercise.

The trial showed that heart rate increases, and that QTc prolongs in response to the stress. The QT prolongation persisted for 20 minutes. As a secondary purely emotional stressor unheralded phone calls were made to the participants during the trial with similar results, there was no difference in response between cases and controls. While the trial showed that the QT interval is labile and strongly affected by emotion, there is nothing intrinsically different in response between the patients and the controls. Reassuringly, there was no evidence that the cases carried a background alteration in QT sensitivity.

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0265607

Authors: Watson GM, Sutherland J, Lacey C, Bridgman PG (2022)

by Alex Dashwood 22 February 2022

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