Sudden death in patients with hypertrophic cardiomyopathy (HCM) is sometimes associated with exercise, but that may be just medical reductionism looking for any answer. Instead, a number of factors could have been involved, since nearly 80% of patients in the study had no symptoms and only one in five had been diagnosed with HCM before their death, according to research presented at ESC Congress 2016 today by Dr Gherardo Finocchiaro, a cardiologist at St George's University of London.
That's no reason to take up Crossfit, with its ridicule of people who have had organ injury thanks to Greg Glassman's desire to get rich at any cost, but it's not a reason to avoid exercise at all.
The study investigated the circumstances and demographics of sudden cardiac death in 184 HCM patients enrolled from 1994 to 2014 at St George's Hospital Cardiac Pathology center. All patients underwent a detailed post-mortem examination by an expert cardiac pathologist to confirm the diagnosis of hypertrophic cardiomyopathy. Clinical information was obtained from referring coroners. Patients were 39 years of age on average and 70% were men.
Only 20% of patients had an ante-mortem diagnosis of HCM. Just 22% of patients had exhibited cardiac symptoms such as palpitations, dyspnoea, syncope and chest pain.
Finocchiaro said, "HCM is an inherited heart muscle disease with variable clinical expression and natural history. It is characterized by hypertrophy of the left ventricular walls ('thick heart muscle'). Sudden cardiac death (SCD) is a relatively common cause of mortality in patients with HCM. It is caused by fatal arrhythmias which can be effectively treated with implantable cardioverter defibrillators (ICDs).
"Diagnosis is often missed during life and HCM may be a 'silent killer' where the first manifestation of the disease is commonly SCD. In fact patients are often asymptomatic (78% in our study) and the diagnosis may be triggered by an abnormal electrocardiogram done in the context of sport screening or for other medical reasons."
SCD occurred at various ages, with the highest prevalence in the third and fourth decades of life (figure 1). The majority of patients died during rest (almost 80%). Of the 149 patients who died at rest, 22 (12%) died during sleep. SCD during exertion occurred more frequently in young male patients. Twenty (11%) of sudden death patients were recreational or competitive athletes.
Dr Finocchiaro said, "Our findings are relatively new and are based on a large sample size. We showed that SCD in HCM occurs relatively rarely during sport activity, but more often at rest and sometimes during sleep.
"These data suggest that exercise induced SCD is relevant only in young males. Therefore the recommendations to avoid competitive sport in individuals with a clear HCM phenotype should be adjusted according to a risk assessment that considers important variables such as gender and age."