The researchers also report that left-handed and ambidextrous subjects appeared to have a "distinctly" lower risk of SCD than right-handed patients, suggesting, they say, a role for the brain in this relationship.

The new report appears online as a rapid access paper, prior to publication in the December 2003 issue of Stroke.[1]

"Our findings may have clinical implications, eg, the use of -blocking drugs in patients with left-sided brain infarction, and need to be corroborated in other clinical studies," the researchers, with first author Dr Ale Algra (Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, the Netherlands), conclude.

Increased risk from right-sided infarction

Data from clinical trials in stroke have suggested that sudden death is not rare in stroke patients, Algra et al write; analysis from three secondary-prevention trials, for example, yielded an incidence of 1.0% (95% CI0.8-1.1), indicating "the relevance of sudden death in these patients and the opportunity to study determinants of sudden death in stroke trials."

There is a strong positive relationship between decreased heart-rate variability and sudden death, and brain infarction has been implicated in lowering levels of heart-rate variability, they note. Patients with acute right-sided hemispheric lesions have been shown to have lower levels of heart-rate variability than those with infarction on the left, and lesions of the right insula have been shown most likely to be associated with decreases in heart-rate variability.

In this study, they used data from NASCET, a large randomized trial of carotid endarterectomy in patients with carotid disease and a previous transient ischemic attack or minor ischemic stroke, to examine the relationship between the presence, side, and insular site of brain infarction and the long-term risk of SCD in these patients. They also looked at the relationship between handedness and subsequent SCD.

The analyses were done using three definitions of sudden death based on time: death within 10 minutes of symptom onset (witnessed and with reliable information); death within one hour of symptom onset (also witnessed and reliable); and death within 24 hours of onset (witnessed without reliable data on timing or the patient was found dead unexpectedly). Death within 24 hours was used for the primary analysis.

Of the 2885 patients in NASCET, 663 deaths occurred, 410 from vascular causes, and 217 of these died within 24 hours of symptom onset. Annual risk of death within 24 hours in this data set was 1.5% (95% CI 1.3-1.7). Of the patients, 2778 had a baseline CT or MRI available, and at least one area of brain infarction was present in 1483, or 53.4%, on the left (n=471), the right (n=477), or both (n=535).

Algra et al report that the five-year risk of sudden cardiac death was highest in those with left-sided or bilateral infarction, compared with no or right-sided infarction, and hazard ratios indicated an increased risk with lesions in these areas even after adjustment for other risk factors. The finding, Algra says in a press statement from the AHA, was "quite the opposite of what we expected."

Complete informations and data are available on the original website TheHeart.org