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“With a most constant heart”: an electrocardiographic study of the heart before and after it breaks

A 2019/2020 Summer Studentship research project

Whether broken heart syndrome causes a permanent change in the electrical activity of the heart is unknown. This study would allow us to see whether the electrical function of the heart before the broken heart was normal, and whether it changed after the heart had recovered.

Student: Isla Evison
Supervisors: Dr Paul Bridgman, Consultant Cardiologist, Mr George Watson
Sponsor: Canterbury Medical Research Foundation

Introduction

Astute observers of humanity have long known that the heart can break. Following the major Canterbury earthquakes, Christchurch Hospital has seen unprecedented case clusters of broken heart syndrome, also known as stress cardiomyopathy or takotsubo syndrome. This has been of widespread public and scientific interest. Our collaborative group, which for the last two years has included a summer student, have been in many news media reports and published multiple scientific publications on this topic.

Broken heart syndrome is usually a self-limiting condition with sudden onset and full recovery over the following weeks. There are several ECG changes that commonly occur during the acute phase – the most prominent is prolongation of the QT interval. It is presumed that QT prolongation is a transient abnormality, with a normal QT before and after the cardiomyopathy, but no study has systematically tested this. There are case reports of broken heart syndrome occurring in association with congenital long QT syndrome and in patients with rare K and Ca channel genetic mutations, yet it is presumed that in other cases the QT interval was normal before the cardiomyopathy developed.

Aims

  • To measure the QT in ECGs recorded prior to the patient developing broken heart syndrome and in late follow-up ECGs to directly compare the QT interval before and after the acute event.
  • Recurrence is infrequent but a small number of patients may suffer from a cluster of episodes. In the small subset of our cohort who had recurrence, we will compare QT between episodes with the presumed final post-recovery QT.
  • Beta-blockers are frequently commenced in patients with broken heart syndrome. There is no data on their effects on QT in the condition. Whilst beta-blockers are used to treat some forms of congenital long QT syndrome, they can also be pro-arrhythmic by contributing to bradycardia-mediated Torsades de Pointes. We aim to compare the QT interval in patients who did and did not receive beta-blockade.

Method

Since the September 2010 Christchurch earthquake, the Cardiology Department has maintained a log of broken heart syndrome cases. We now have over 200 patients in the registry. The study is a retrospective case-note review of this cohort, involving measuring the QT interval on the ECGs before and after each patient’s broken heart syndrome event, and documenting the medications that the patients were on at each of these timepoints. The student would be expected to construct an Excel spreadsheet to allow us to analyse the relationship between the QT interval and patient factors such as age, echocardiographic takotsubo variant, medications, and genetic abnormality. This may lead to an abstract presentation through a poster at the 2020 New Zealand Cardiac Society Annual Scientific Meeting in Dunedin.

Student researcher’s component of the study

Throughout the studentship, the student will have the opportunity to experience clinical cardiology by attending Cardiology Department clinical meetings and some ward rounds and clinics.

Student Prerequisites

Second- or third-year medical student

How to apply

Email paul.bridgman@cdhb.health.nz