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Sudden cardiac death in the spotlight

27 Aug 2021

This year’s Spotlight Track – on sudden cardiac death (SCD) – features 20 dedicated sessions, which begin this morning with the first of three ‘Meet the Experts’. There is much to learn from around the world, with five joint sessions in conjunction with international cardiology societies. Three sessions discuss using digital methods in the fight against SCD and, across the Spotlight Track, a range of settings are considered including SCD in heart failure and hypertension, and in apparently healthy individuals, such as pregnant women and young athletes.

Important questions will be raised about prediction and prevention. In one of the highlights from the abstract-based programme on SCD, Doctor Richard Jones (National Heart and Lung Institute, Imperial College London, UK) will present findings on how imaging may be useful, namely whether infarct characterisation using cardiovascular magnetic resonance (CMR) with late gadolinium enhancement (LGE) may be able to predict SCD in patients with coronary heart disease (CHD).

Patients with stable CHD and no secondary-prevention implantable cardioverter defibrillator (ICD) indication were prospectively enrolled into a registry. CMR with LGE was used to measure the mass of the peri­infarct zone (PIZ) and core infarct, while specific morphological and texture-related features of the fibrosis microstructure were studied using bespoke image-processing algorithms. The primary outcome was SCD or aborted SCD.

The mean age of the 437 enrolled patients was 64 years, mean left ventricular ejection fraction (LVEF) was 47% and 91% had LGE. Over a median follow-up period of 6.3 years, 49 (11.2%) patients experienced the primary outcome. Patients with higher PIZ mass had an increased risk of the primary outcome (10-­year risk 0.7%, 24.0% and 37.8% for patients with PIZ mass <5.66 g, 5.66–12.28 g and ≥12.29 g, respectively; p<0.001). On multivariate analysis, PIZ mass and core infarct mass remained independently associated with the primary outcome (per 10 g: hazard ratio [HR] 1.93; 95% confidence interval [CI] 1.22 to 3.06; p=0.005 and HR 1.27; 95% CI 1.03 to 1.58; p=0.03, respectively). Of note, including both scar metrics to a prediction model of conventional parameters improved its discrimination ability (Harrell’s C­-statistic 0.76 to 0.82). Importantly, LVEF did not associate with the primary outcome when LGE parameters were included in the prediction models.

Analysis of the scar microstructure identified several shape­-based features that were associated with the primary outcome, including core infarct transmurality, radiality and interface length, and the number of PIZ islets.

Dr. Jones concludes that CMR characterisation of myocardial fibrosis can accurately predict long-term SCD risk and highlights the use of the identified measures as a potential avenue towards a more personalised approach to ICD implantation decisions.


Another way that SCD may be predicted, and thus prevented, is by gaining a better understanding of any early warning signs – the prodromal symptoms – that precede the cardiac arrest.

In an e-Poster, Doctor Nertila Zylyftari (Gentofte Hospital, Copenhagen University Hospital, Hellerup, Denmark) and colleagues describe their work on investigating prodromal symptoms among patients who called emergency and non-emergency medical help services prior to their out-of-hospital cardiac arrest (OHCA). The Danish Cardiac Arrest Registry was used to identify adult patients who had an OHCA, and these details were linked to calls made to a non­-emergency medical helpline and to the emergency medical services.

Among the 974 patients who called helplines within 30 days before OHCA, 816 patients (males 57%, median age 76 years) had a registered symptom, with some patients calling more than once (1,145 calls by 816 patients). The most reported group of symptoms was ‘other’ (29%), which contained a diverse group of symptoms that did not fit into specific categories, including cardiac symptoms, breathing problems, CNS/unconsciousness, trauma/exposure etc. The second most-reported symptom was breathing problems (15%).

When analysed by time period, ‘other’ remained the most common symptom group (30%) within the 0–7 days before OHCA, followed by CNS/unconsciousness (17%) and breathing problems (11%). Within 8–30 days before OHCA, ‘other’ was also the most common (29%), followed by breathing problems (19%) and trauma/exposure (17%).

When analysed by call type, most patients (61%) called the non-­emergency medical helpline, where ‘other’ (35%) and abdominal/back/urinary (14%) symptom groups were the most common. While breathing problems (24%) and CNS/unconsciousness (21%) were highly reported among calls to the emergency medical services.

Another e-Poster, by Mr. Filip Gnesin (Nordsjaellands Hospital, Hilleroed, Denmark), also found that breathing problems were commonly reported among patients before OHCA. His study looked at emergency calls made within 24 hours prior to OHCA and used similar methodology.

Among 4,071 patients with OHCA, 481 (12%) made 539 pre-arrest calls. The most commonly reported symptoms were breathing problems (59%), confusion (23%), unconsciousness (20%), chest pain (20%) and paleness (19%).

These analyses, identifying prodromal symptoms of OHCA, help to build up a clearer picture of the warning signs – further work on how future cardiac arrests can be prevented is needed.


Want to know more about these studies?

Jones R, et al

Zylyftari N, et al

Gnesin F, et al


Check out the Spotlight on SCD Track here: