Heart rate turbulence and death due to cardiac decompensation in patients with chronic heart failure.

BACKGROUND: As treatment strategies for patients with chronic heart failure (HF) become more sophisticated, identifying patients at high risk of death and predicting mode of death is important. The aim of this study was to explore the potential utility of heart rate turbulence (HRT) to identify patients with HF at high risk of death. METHODS AND RESULTS: In a prospective study, 553 ambulant outpatients age 63+/-10 with symptoms of HF and evidence of cardiac dysfunction were recruited. All patients underwent 24-h Holter ECG recordings, which were analysed for arrhythmias, heart rate variability and HRT a measurement that is thought to quantify cardiac autonomic regulatory mechanisms. Baseline chest radiograph, biochemistry and 12-lead electrocardiograms were also obtained. In patients with HRT measurements at 5 years follow up, 146 patients had died, 59 due to decompensated HF. Independent predictors of death from decompensated HF at 5-year follow up (Cox proportional hazard model) were HRT slope (HR for 10% increment 0.84, 95% CI 0.77-0.91), serum sodium (HR for 10% increment 0.75, 95% CI 0.62-0.91) and serum creatinine (for 10% increment HR 1.14, 95% CI 1.08-1.19) all P<0.01. These 3 variables combined had excellent discrimination between patients dying of decompensated HF and other patients, C-statistic=0.82. CONCLUSIONS: In patients with mild-to-moderate HF, HRT slope is an independent predictor of death due to decompensated HF. HRT may have the potential to help tailor therapy in this patient group.

Changing characteristics and mode of death associated with chronic heart failure caused by left ventricular systolic dysfunction: a study across therapeutic eras.

BACKGROUND: Therapies for patients with chronic heart failure caused by left ventricular systolic dysfunction have advanced substantially over recent decades. The cumulative effect of these therapies on mortality, mode of death, symptoms, and clinical characteristics has yet to be defined. METHODS AND RESULTS: This study was a comparison of 2 prospective cohort studies of outpatients with chronic heart failure caused by left ventricular systolic dysfunction performed between 1993 and 1995 (historic cohort: n=281) and 2006 and 2009 (contemporary cohort: n=357). In the historic cohort, 83% were prescribed angiotensin-converting enzyme inhibitors and 8.5% were prescribed ß-adrenoceptor antagonists, compared with 89% and 80%, respectively, in the contemporary cohort. Mortality rates over the first year of follow-up declined from 12.5% to 7.8% between eras (P=0.04), and sudden death contributed less to contemporary mortality (33.6% versus 12.7%; P<0.001). New York Heart Association class declined between eras (P<0.001). QTc dispersion across the chest leads declined from 85 ms (SD, 2) to 34 ms (SD, 1) and left ventricular end-diastolic dimensions declined from 65 mm (SD, 0.6) to 59 mm (SD, 0.5) (both P<0.001). CONCLUSIONS: Survival has significantly improved in patients with chronic heart failure caused by left ventricular systolic dysfunction over the past 15 years; furthermore, sudden death makes a much smaller contribution to mortality, and noncardiac mortality is a correspondingly greater contribution. This has been accompanied by an improvement in symptoms and some markers of adverse electric and structural left ventricular remodeling.

Spectral analysis, death and coronary anatomy following cardiac catheterisation.

OBJECTIVE: To establish the associations and prognostic utility of angiographic, clinical and HRV parameters in a large cohort of patients undergoing diagnostic cardiac catheterisation (CC). METHODS: Patients undergoing CC as elective day cases were enrolled at a single tertiary center from September 2001 to January 2003. Patient data, serum biochemistry, current drug therapy, catheter reports and five minute high resolution electrocardiograph (ECG) recordings were prospectively recorded and validated in an electronic archive. ECG recordings were used to generate time domain (SDNN (standard deviation of NN intervals)) and spectral HRV parameters (low frequency (LF) and high frequency (HF) power). Significant associations between dichotomized HRV variables and covariates were investigated using binary logistic regression. The independent prognostic ability of clinical markers was evaluated using the Cox proportional hazard model. RESULTS: 841 consecutive consenting patients of mean age 61+/-10 years were recruited into the study with a mean follow-up period of 690+/-436 days. In multivariate analysis decreasing LF spectral power was independently associated with proximal right coronary stenosis OR (odds ratio)=1.65 (95% CI=1.16-2.36), P=0.006 and to all cause mortality OR=5.01 (95% CI=1.47-17.01), P=0.010. Increasing LF power was also independently associated with normal coronary angiograms in patients investigated suspected coronary disease without a confirmed prior history of a coronary ischaemic event OR=2.16 (95% CI=1.26-3.73), P=0.002. CONCLUSIONS: Reduced LF power independently predicts all cause mortality in a large cohort of patients receiving medical therapy after elective CC. LF power was also independently associated with >75% proximal RCA stenosis.