Maximal/exhaustive treadmill test features in patients with temporal lobe epilepsy: Search for sudden unexpected death biomarkers

Autonomic dysfunction may account for sudden unexpected death in patients with epilepsy (PWE). On the other hand, low cardiovascular fitness, which may affect autonomic function, is a risk factor for sudden death and all cause mortality in the general population. Little is known about autonomic variables and cardiovascular response to exercise in PWE. We submitted thirty consecutive PWE with no known cardiovascular diseases to maximal treadmill test, comparing them with matched controls. All individuals were submitted to clinical assessment, 12-lead electrocardiogram (ECG) and echocardiogram to exclude cardiovascular disease. Maximal/exhaustive treadmill test using the Bruce protocol was then performed. Clinical-epidemiological features were similar in both groups, regarding age, sex, body mass index and traditional cardiovascular risk factors. PWE achieved a lower peak heart rate (163.8 +/- 21.28 bpm x 180.9 +/- 12.52 bpm; p = 0.002), lower duration of exercise (673.6 +/- 148.27 s x 784.4 +/- 155.72 s; p = 0.004), lower Duke Score (11.8 +/- 2.48 x 13.4 +/- 2.28; p = 0.02) and lower achieved metabolic equivalent of task (MET) (12.8 +/- 2.49 x 14.5 +/- 2.46; p = 0.006). Chronotropic incompetence was more frequent in PWE. Female gender, age of epilepsy onset, number of secondarily generalized seizures and polytherapy were associated to lower cardiovascular fitness in multiple linear regression. Increased risk for SUDEP in PWE may be associated with autonomic disturbances of the cardiovascular system secondary to low cardiovascular fitness.