“There is one risk factor for premature death that makes all others fade into relative insignificance,” said Dr. Malcolm Kendrick, a UK cardiologist, “and that is heart rate variability (HRV).” According to Kendrick, none of the traditional risk factors for heart disease can compare with this level of increased risk.

According to Dr. Kendrick, the heart rate is not constant. It ‘hunts’ up and down, and changes rapidly in response to various stimuli. As an example, if we are challenged physically or mentally our heart rate will rapidly rise. When we relax it falls. Our heart rate is altering or adapting from from beat to beat.

Kendrick sites a 10-year study of an elderly population in Finland (Circulation 1998;97:2031-6.) All patients were over age 65. Two groups were compared – those with ‘good’ HRV (a higher level of beat to beat variation) and those with ‘bad’ HRC (a lower level of variation). After 10 years, the chances of being alive were more than 70 percent for those with a higher level of HRV and under 20 percent for those with poor HRV.

Kendrick states that a wide range of conditions cause a reduction in HRV, including cancer, diabetes, depression, and coronary heart disease (sticky, clot-prone blood). A growing body of evidence suggests that stress and depression can significantly reduce HRV (Bess Taylor C, Conrad A, Wilhelm FH. Psychological and cortisol responses to psychological stress. Psychosomatic Medicine 2006; 68:538-546.)

Kendrick concludes that stress, or a poor reaction to various stressors, may indeed be the underlying cause of reduced HRV. Kendrick suggests that poor HRV is the single most important predictor of overall health and mortality there is. “Ignoring it is to disregard an entire area where we may be able to treat the underlying drivers of ill-health and premature mortality,” writes Kendrick.

Dr Malcolm Kendrick is a GP in south Manchester England