Camm: “The true incidence of sudden cardiac death in USA and Europe is unknown”

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By Angela Gonzalez

John Camm, St Georges University of London, United Kingdom, overviewed the incidence of sudden cardiac death in Europe and USA at the European Heart Rhythm Association (EHRA)-Europace Congress in Madrid, Spain (26-29 June 2011). Camm told delegates “The true incidence of sudden cardiac death in USA and Europe is unknown.” There is no current data of sudden cardiac death figures in Europe as a whole and although there are some US studies available, there are disparities in the figures presented, he commented.

Camm made reference to Kong et al‘s paper: “Systematic review of the incidence of sudden cardiac death in the United States.” The review, directed by the Sudden Cardiac Arrest Thought Leadership Alliance’s (SCATLA) Think Tank and published this year in the Journal of the American College of Cardiology, showed that “The estimated US annual incidence of sudden cardiac death varied widely from 180.000 to more than 450.000 among six clinical studies” these variations, the authors wrote, were due to different data sources ranging from 1980 to 2007, definitions of sudden cardiac death, case ascertainment criteria, methods of estimation/extrapolation and sources of case ascertainment. “The true incidence of sudden cardiac arrest and/or sudden cardiac death in the USA remains unclear, with a wide range in available estimates,” the authors wrote.

The situation in Europe toward reliability of sudden cardiac death figures tends to be more problematic than in the USA. Camm commented: “The biggest problem with regard to working out the size of the problem in sudden cardiac death is that we have practically no data at all in Europe.” There are some studies on sudden cardiac death incidence made independently in some European countries, however “There has not been a requirement for an international, pan-European concept in Europe,” Camm said.

Referring to some of the European studies, Camm highlighted Straus S et al‘s Dutch study which found that the sudden cardiac death rate in The Netherlands dropped from 1996 to 2000 from 1.07 per 1000 person-years to 0.8 per 1000 person-years. The study also showed that the risk of sudden cardiac death was 2.3-fold higher in men than in women, increased with age and most cases occurred at home. Preventive medicine, improved treatment of myocardial infarction and ICD use has contributed to these decreasing figures, Camm said.

Camm also referred to studies on the incidence of sudden cardiac death in the young highlighting that this is a particular problem that is possibly declining in athletes but not in general. He cited a recent Danish study by Winkel et al, published in the European Heart Journal. People aged between one and 35 years (5.38 million) were assessed by systematic evaluation of all deaths from 2000 to 2006. The researchers identified 625 cases of sudden unexpected death, which counted for 10% of all deaths, of which 156 (25%) were not autopsied. Of the 469 autopsied cases, 314 were due to sudden cardiac death. The authors concluded that the incidence rate per 100.000 person-years was 2.8, included not autopsied cases. Camm noted that this incidence rate coincides with the study by Margey RJ et al, which indicated 2.85 incidence of sudden cardiac rate per 100.000 person-years in the Irish population aged between 14 to 35 years.

Camm also commented that the trend in the athlete population has shown a significant decrease. He made reference to Corrado et al‘s study which analysed the annual incidence of sudden cardiac death in young athletes in the Veneto region of Italy from 1979 to 2004. The results showed that the annual incidence of sudden cardiovascular death in athletes decreased by 89% (from 3.6/100.000 person-years in 1979-1980 to 0.4/100.000 person-years in 2003-2004). “The incidence of sudden cardiovascular death in young competitive athletes has substantially declined in the Veneto region of Italy since the introduction of a nationwide systematic screening,” the authors wrote.

To conclude, Camm suggested the need to get more accurate European data on sudden cardiac death with the implementation of large multicentre studies to identify more precise strategic risk stratification and preventive measures. He shared Kong et al’s position: “As reliable estimates of sudden cardiac death incidence are important for improving risk stratification and prevention, future efforts are clearly needed to establish uniform definitions of sudden cardiac arrest and sudden cardiac death and then to prospectively and precisely capture cases of sudden cardiac arrest and sudden in the overall US population.”