Wall Thickness No Predictor Of Cardiomyopathy Mortality Risk

Aggressive prophylactic therapy is not justified in patients with a risk of sudden death who have hypertrophic cardiomyopathy and a left-ventricular wall thickness of 30 mm or more but no other risk factors.

At the same time, according to the study by Dr. Perry Elliott and colleagues from St George’s Hospital Medical School, London, United Kingdom, most sudden deaths occurred in patients with wall thickness less than 30 mm. Thus, “the presence of mild hypertrophy cannot be used to reassure patients that they are at low risk,” they warn.

Hypertrophic cardiomyopathy (HCM) is a genetic disorder of the heart muscle and is the most common cause of sudden death in competitive athletes and young people.

The researchers note that a recent study in the United States suggests that severe left-ventricular hypertrophy (maximum wall thickness 30 mm) in patients with hypertrophic cardiomyopathy is associated with a risk of sudden cardiac death sufficient to warrant possible implantation of a cardioverter defibrillator (ICD). However, the prognostic significance of left-ventricular hypertrophy in relation to other clinical risk factors is poorly characterized.

In the investigation, the clinicians studied 630 patients consecutively referred to the hospital. Their mean age was 37 years; 382 were male and mean follow-up was 59 months. Patients underwent two-dimensional and Doppler echocardiography, upright exercise testing and Holter monitoring.

Researchers found that 39 patients died suddenly or had an appropriate ICD discharge, nine died from progressive heart failure, 11 from other cardiovascular causes and 23 from non-cardiac causes. There was a trend towards higher probability of sudden death or ICD discharge with increasing wall thickness.

Of the 39 patients who died suddenly or had an ICD discharge, ten had a wall thickness of 30 mm or more. These patients had higher probability of sudden death or ICD discharge than patients with wall thickness less than 30 mm.

Dr. Elliot and colleague declare that “the most important implication of this and other studies is that no single risk factor, with the possible exception of a history of ventricular fibrillation, can be used as a catch-all screening test in assessment of sudden-death risk in patients with hypertrophic cardiomyopathy.

“The excellent survival in the 40 percent of patients with a wall thickness of 30 mm or more and no other clinical risk factors shows that a wall thickness of this magnitude cannot by itself be used as justification for implantation of an ICD in patients with hypertrophic cardiomyopathy. Nor does it support the assertion that the absence of massive hypertrophy can be used to reassure patients.”

At the same time, the clinicians conclude, their study does “suggest that wall thickness may be a useful risk marker when it is included in a broader clinical risk assessment that takes into account other established risk factors, such as family history, symptoms, the presence of arrhythmia, and exercise blood-pressure responses.”

Lancet 2001;357:420-24.