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• Where do we start to tackle unexpected sudden cardiac death?
  Robert J MacFadyen
  Published on: 23 November 2015

• Published on: 23 November 2015

  Where do we start to tackle unexpected sudden cardiac death?

  • Robert J MacFadyen, Consultant Cardiologist
  • Other Contributors:
    • Ali Hamaad

  Dear Editor

  Herlitz and colleagues [1] paint a rather gloomy picture of the impact of 20 years of effort in managing out of hospital cardiac arrest. Their large population observations are very valuable and will have a familiar feel to many practising cardiologists. The study showing survival rates over the last 20 years have not improved is comparable to previous studies.[2,3] If survival rates for victims of out-...

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  Dear Editor

  Herlitz and colleagues [1] paint a rather gloomy picture of the impact of 20 years of effort in managing out of hospital cardiac arrest. Their large population observations are very valuable and will have a familiar feel to many practising cardiologists. The study showing survival rates over the last 20 years have not improved is comparable to previous studies.[2,3] If survival rates for victims of out- of-hospital cardiac arrest are to improve, then one possible avenue is to explore in greater detail the events leading up to the arrest. One aspect we feel should be highlighted more clearly is the critical impact of patient contact prior to any event.

  Patients with known illness may contact support services early or may defer contact such that arrest occurs in an unmonitored setting clearly putting resuscitation attempts and survival at a disadvantage. This is poorly defined in what is otherwise an extensively researched area. Second, those patients with no prior medical contacts may react differently again either presenting with undiagnosed or ‘atypical’ symptoms to one or other health professional. They may be treated for a non-cardiac diagnosis that proves incorrect only in retrospect. Whilst data on previous medical history (acute myocardial infarction, angina pectoris, congestive heart failure and smoking status) were included in Herlitz database there was typically no data on victims with no documented previous medical history, and in particular whether these victims have any contact with medical services in the hours or days prior to the event. While information from relatives may be difficult to collect and perhaps painful for the individual families, they might provide useful details on circumstances prior to an individual arrest.

  What we need to define by such work is whether there is a window of opportunity for early intervention in these events, which could be critical in defining individual outcome. It is not known what proportion of victims of out-of-hospital cardiac arrest have occult cardiac or non- cardiac disease whose first presentation is the cardiac arrest. This would be an important finding as it would mean that appropriate diagnostic effort could potentially abort these events. Unfortunately there was minimal data in the current report on a final pathological diagnosis on discharge from hospital.

  The second useful point to emerge from Herlitz’s work involves the poorer survival associated with diuretic use. The authors understandably suggested the common association with cases of ‘congestive heart failure’. This is a common presumption but in many studies a significant proportion of people who are on diuretic therapy do not have any evidence of left ventricular dysfunction even with a presumed ‘heart failure’ diagnosis in the community.[4] That impaired systolic function is strongly associated with sudden cardiac death is not at issue. Thiazide diuretic treatment is far more often a marker of hypertension and this would be more likely to be associated with occlusive coronary events than primary or secondary arrhythmia in systolic dysfunction. Clearly this is important in terms of the best therapeutic strategies that for coronary occlusive disease would be accelerated revascularisation rather than for example device management of arrhythmia in an already impaired left ventricle. Unfortunately the population data presented by Herlitz or indeed from any comparable database do not allow this to be defined.

  In summary Herlitz large epidemiological survey serves to underline the pressing need for new approaches to out of hospital arrest over and above the fine tuning of resuscitation algorithms which are basically showing little real progress despite the huge efforts of those concerned. The published data look bleak on first reading but the outcome may be improved by more detailed individual case recognition and should start with more research on the perception of illness by patients in these critical cases. Are all sudden arrests truly sudden/instantaneous or could there be an early pattern of atypical symptoms in some prior to the arrest? Surely Herlitz summary data shows well enough that continuing with the current patterns is just not good enough?

  References (1) Herlitz J, Bång A, Gunnarsson J, Engdahl J, Karlson BW, Lindqvist J, Waagstein L. Factors associated with survival to hospital discharge among patients hospitalised alive after out of hospital cardiac arrest: change in outcome over 20 years in the community of Göteborg, Sweden. Heart 2003;89:25-30.

  (2) Nichol G, Detsky AS, Steill IG, O’Rourke K, Wells G, Laupacis A. Effectiveness of emergency medical services for victims of out-of-hospital cardiac arrest: a metaanalysis. Ann Emerg Med 1996;27:700-710.

  (3) Eisenberg MS, Horwood BT, Cummins RO, Reynolds-Haertle R, Haerne TR. Cardiac arrest and resuscitation: a tale of 29 cities. Ann Emerg Med 1990;19:179-180.

  (4) Davies MK, Hobbs FDR, Davis RC, Kenkre JE, Raolfe AK, Hare R, Wosornu D, Lancashire RJ. Prevalence of left-ventricular systolic dysfunction and heart failure in the Echocardiographic Heart of England Screening Study: a population based study. Lancet 2001;358:439-44.

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  Conflict of Interest:
  None declared.

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