Poor ability to slow heart rate predicts death after heart attack

Heart attack survivors who lack variability in their heart rate are at a greater risk of death, according to a paper in this week's issue of The Lancet. The study found that measuring the ability of the heart rate to slow down (heart rate deceleration capacity) was a better predictor of mortality after heart attack than current measures.

Studies suggest that the risk of death in patients who have had a heart attack can be reduced by implantation of a defibrillator. The gold-standard measure used to predict risk of death is the extent of impairment of the left-ventricle of the heart.

Georg Schmidt (Munich University of Technology, Munich, Germany) and colleagues investigated an alternative measure – heart rate deceleration capacity. A person's heart rate is not perfectly regular but varies with the breathing cycle, speeding with inspiration and slowing down on exhalation. Heart rate can also speed up with decreasing arterial pressure and slow down with increasing arterial pressure. The capacity of the heart rate to vary is a marker for wellbeing.

By analysing data from 2,700 patients who had had a heart attack the investigators found that heart-rate deceleration capacity was a stronger predictor of mortality than the left ventricle impairment measure or standard measures of heart rate variability.

Professor Schmidt states: "Deceleration capacity substantially improves risk prediction in survivors of acute myocardial infarction [heart attack]...Our findings show that this new measure can detect high-risk patients even if the current gold-standard measure fails."

See also accompanying Comment.

Contact: Georg Schmidt, MD, Professor of Cardiology, Technische Universität München 1, Medizinische Klinik, Klinikum r.d.Isar, Ismaninger Str. 22, 81675, Munich, Germany. T) +49 89 41402352 gschmidt@tum.de

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