Background: Deceleration capacity (DC) is a novel electrocardiography (ECG) parameter characterizing the overall capacity of slowing down the heart rate. The aim of this study was to evaluate clinical and ECG covariates of DC in patients with the first episode of ST-segment elevation myocardial infarction (STEMI) treated with primary angioplasty.
Methods: Deceleration capacity, heart rate variability (HRV) and heart rate turbulence (HRT) were assessed from 24-hour ECG Holter recordings in 70 patients (66 male, mean age 57 years) with STEMI. Deceleration capacity was evaluated as continuous or dichotomized (£ 4.5 vs. > 4.5 ms) variable.
Results: The median value of DC was 5.12 ms. Thirty patients (43%) had abnormal DC (£ 4.5 ms). The abnormal DC was more common in female, older and hypertensive patients. Although DC was not associated with either STEMI localization or left ventricular ejection fraction, it was significantly correlated with mean heart rate, standard HRV indices and HRT slope. Multivariate logistic regression showed that hypertension (OR = 3.23, 95% CI = 1.1-9.9, p = 0.039) and mean heart rate > 70 beats/minute (OR = 6.05, 95% CI = 2.0-18.4, p = 0.001) were independently associated with abnormal DC.
Conclusions: Deceleration capacity in patients with the first STEMI treated with primary angioplasty is influenced by age, gender, hypertension and heart rate, but not the location of myocardial infarction or left ventricular ejection fraction. Correlation between DC and HRV indices suggests that DC is related to autonomic modulation of heart rate.