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Introduction: Repolarization dynamics, reflecting adaptation of QT to changing heart rate, is considered a marker of unfavorable prognosis in patients with heart diseases. We aimed to evaluate the prognostic value of QT/RR slope in predicting total mortality (TM) and sudden death (SD) in patients with congestive heart failure (CHF)., Methods and Results: In 651 sinus rhythm patients with CHF in NYHA class II-III enrolled in the MUSIC study, 24-hour Holter monitoring was performed at enrollment to assess slope of the QTa/RR (QT apex) and QTe/RR (QTend) during the entire 24-hour Holter recording and separately during day and night periods. Patients were followed for a median of 44 months, with the primary endpoint defined as TM and the secondary as SD. Analysis of repolarization dynamics was feasible in 542 patients (407M), mean age 63 years, 83% in NYHA class II, 49% with ischemic cardiomyopathy, with mean LVEF 37%. Mean value of QTa/RR slope was 0.172 and QTe/RR was 0.193. During the 44-month follow-up there were 119 deaths including 47 SD. Nonsurvivors were characterized by steeper QT/RR slopes. Increased QT/RR slopes during the daytime (>0.20 for QTa and >0.22 for QTe) were independently associated with increased TM in multivariate analysis after adjustment for clinical covariates with respective hazard ratios 1.57 and 1.58, P = 0.002. None of the dynamic repolarization parameters was associated with increased risk of SD in the entire population., Conclusions: Abnormal repolarization dynamics reflected as increased daytime QT/RR slopes is an independent risk stratifier of all-cause mortality in patients with chronic heart failure.

Sudden cardiac death (SCD) is a leading cause of mortality with an incidence of 3 million cases per year worldwide. Therapies for patients who have survived an SCD episode or have a high risk of developing lethal ventricular arrhythmia are well established and depend mainly on risk stratification. In this study we investigated the suitability of the non-linear measure compression entropy (Hc) for improved risk prediction in cardiac patients. We recorded 24-h Holter ECG for 300 patients with congestive heart failure (CHF). During a mean follow-up period of 12 months, 32 patients died due to a cardiac event. Hc depends on the compression parameters window length w and buffer length b, which were optimised by analysing a subgroup of patients. Compression entropies based on the beat-to-beat interval (BBI) were subsequently calculated and compared with standard heartrate variability parameters. Statistical analysis revealed significant differences between high- and low-risk CHF patients in standard HRV measures, as well as compression entropy based on the BBI (cardiac death, p = 0.005; SCD, p = 0.02). In conclusion, the implementation of non-linear compression entropy analysis in multivariate analysis seems to be useful for enhanced risk stratification of cardiac death, especially SCD, in ischaemic cardiomyopathy patients.

Objectives: To establish a score or arrhythmic pattern for the prediction of long-term cardiac deaths on patients who have survived to the first acute myocardial infarction., Patients and Methods: We studied prospectively 200 patients that survived at a first myocardial infarction and in whom ambulatory ECG monitoring during 24 hours between days 7th and 18th (mean 12th) from the infarction was performed. The mean follow-up time was 51 +/- 18 months. The number and type of ventricular arrhythmias were analyzed and a score was measured, accordingly with Castellanos and Lown's classifications. An "arrhythmic pattern" or "total punctuation" was defined and compared among two groups: group 1 > 65 points and group 2 < 65 points., Results: The differential characteristics of both groups were: age (60 +/- 9 versus 56 +/- 10 years old; p = 0.004); hypertension (63% versus 29%; p < 0.001); clinic stage II-III (23% versus 11%; p = 0.02); echocardiographic ejection fraction (45 +/- 11% versus 50 +/- 10%; p = 0.04); positive exercise testing (73% versus 56%; p = 0.01); arrhythmias on the exercise test (15% versus 25%; p = 0.006). The long-term cardiac mortality was 25% versus 6% (p = 0.01), with an incidence of sudden death of 11% versus 3% (p < 0.05). Specificity, sensibility, positive predictive value and negative predictive value (reference cut point of 100) were 94, 65, 71 and 91%, respectively., Conclusions: The use of a score of arrhythmic pattern may identify 2 groups of patients with different clinic profiles that probably justify a different long-term prognosis after a first acute myocardial infarction.

A Holter monitorization study was performed in 100 voluntary university students (64 men and 36 women). The mean age was 23.6 years and organic heart disease was ruled out in all cases. Data were analysed in different subgroups including the practice of physical activity and subjects smokers or alcohol consumers. The maximum heart rate (HR) achieved during the wake period was 138.3 +/- 20.43 beat/m. Minimum daytime heart rate was 61.42 +/- 10.32 beat/m and it was below 60 beat/m in 41 subjects. During the nighttime period, the maximum heart rate achieved by the group was 89.34 +/- 11.31 beat/m. Minimum nighttime heart rate was 45.82 +/- 6.35 beat/m. Maximum heart rate in men was 134.3 +/- 21.35 beat/m, while in women was 145.42 +/- 16.36 beat/m. Eighty students presented one or more arrhythmias, among them 28 women and 52 men (p = NS): 92% in sportsmen and women groups as compared with 79% in the non sports practicers, 90% of alcohol consumers and 82% between subjects who smoked and drank, compared with 63% in the non drinkers (p < 0.006). 48% of the subjects presented one or more supraventricular arrhythmias during the daytime or during the nighttime (p = NS). Ventricular rhythm disturbances were found in 20 subjects. There was only one case who had a non sustained ventricular tachycardia of 4 complexes. These disturbances were not increased by practising sport nor by toxic habits. In 15 cases we found sinoatrial block, with a male predominance. Five subjects presented some type of atrioventricular block, 4 of which were alcohol and tobacco consumers.(ABSTRACT TRUNCATED AT 250 WORDS)