Bedside autonomic risk stratification after myocardial infarction by means of short-term deceleration capacity of heart rate

Twenty-four-hour deceleration capacity (DC_24h) of heart rate is a strong predictor of mortality after myocardial infarction (MI). Assessment of DC from short-term recordings (DC_st) would be of practical use in everyday clinical practice but its predictive value is unknown. Here, we test the usefulness of DC_st for autonomic bedside risk stratification after MI.

We included 908 patients after acute MI enrolled in Munich and 478 patients with acute (n = 232) and chronic MI (n = 246) enrolled in Tuebingen, both in Germany. We assessed DC_st from high-resolution resting electrocardiogram (ECG) recordings (<30 min) performed under standardized conditions in supine position. In the Munich cohort, we also assessed DC_24h from 24-h Holter recordings. Deceleration capacity was dichotomized at the established cut-off value of ≤ 2.5 ms. Primary endpoint was 3-year mortality. Secondary endpoint was 3-year cardiovascular mortality. In addition to DC, multivariable analyses included the Global Registry of Acute Coronary Events score >140 and left ventricular ejection fraction ≤ 35%. During follow-up, 48 (5.3%) and 48 (10.0%) patients died in the Munich and Tuebingen cohorts, respectively. On multivariable analyses, DC_st ≤ 2.5 ms was the strongest predictor of mortality, yielding hazard ratios of 5.04 (2.68–9.49; P < 0.001) and 3.19 (1.70–6.02; P < 0.001) in the Munich and Tuebingen cohorts, respectively. Deceleration capacity assessed from short-term recordings ≤ 2.5 ms was also an independent predictor of cardiovascular mortality in both cohorts. Implementation of DC_st ≤ 2.5 ms into the multivariable models led to a significant increase of C-statistics and integrated discrimination improvement score.

Deceleration capacity assessed from short-term recordings is a strong and independent predictor of mortality and cardiovascular mortality after MI, which is complementary to existing risk stratification strategies.