Altered Autonomic Cardiac Control Predicts Restenosis After Percutaneous Coronary Intervention

HRT assessment reviewed: a systematic review of heart rate turbulence methodology

Heart rate turbulence (HRT) is a biphasic reaction to a ventricular premature contraction (VPC) mainly mediated by the baroreflex. It can be used for risk stratification in different disease patterns. Despite existing standards there is a lot of variation in terms of measuring and calculating HRT, which complicates research and application.

OBJECTIVE

This systematic review outlines and evaluates the methodological spectrum of HRT research, especially filtering criteria, parameter calculation and thresholds.

APPROACH

The analysis includes all research papers written in English that have been published before 12.10.2018, are listed on PubMed and involve calculation of HRT parameter values.

MAIN RESULTS

HRT assessment is still being performed in various ways and important specifications of the methodology are not given in many articles. Nevertheless, some suggestions regarding HRT methodology can be made: a normalised turbulence slope should be used to uncouple the parameter from heart rate and frequency of extrasystoles. Filtering criteria as formerly reviewed in the guidelines should be met and mentioned. The minimal number of VPC snippets (VPCSs) as well as new cut-off values for different risks need to be further evaluated. Most importantly, the exact and complete methodology must be described to ensure reproducibility and comparability.

SIGNIFICANCE

Methodical variation hinders comparability of research and medical application. Our continuing questions help to further standardise the measurement and calculation of HRT and increase its value for medical risk stratification.

Spectral analysis related to bare-metal and drug-eluting coronary stent implantation

BACKGROUND

The autonomic nervous system plays a central role in cardiovascular regulation; sympathetic activation occurs during myocardial ischemia.

OBJECTIVE

To assess the spectral analysis of heart rate variability during stent implantation, comparing the types of stent.

METHODS

This study assessed 61 patients (mean age, 64.0 years; 35 men) with ischemic heart disease and indication for stenting. Stent implantation was performed under Holter monitoring to record the spectral analysis of heart rate variability (Fourier transform), measuring the low-frequency (LF) and high-frequency (HF) components, and the LF/HF ratio before and during the procedure.

RESULTS

Bare-metal stent was implanted in 34 patients, while the others received drug-eluting stents. The right coronary artery was approached in 21 patients, the left anterior descending, in 28, and the circumflex, in 9. As compared with the pre-stenting period, all patients showed an increase in LF and HF during stent implantation (658 versus 185 ms2, p = 0.00; 322 versus 121, p = 0.00, respectively), with no change in LF/HF. During stent implantation, LF was 864 ms2 in patients with bare-metal stents, and 398 ms2 in those with drug-eluting stents (p = 0.00). The spectral analysis of heart rate variability showed no association with diabetes mellitus, family history, clinical presentation, beta-blockers, age, and vessel or its segment.

CONCLUSIONS

Stent implantation resulted in concomitant sympathetic and vagal activations. Diabetes mellitus, use of beta-blockers, and the vessel approached showed no influence on the spectral analysis of heart rate variability. Sympathetic activation was lower during the implantation of drug-eluting stents.

Effects of cigarette smoke on Holter ECG recordings in patients with arterial hypertension. Part 2: Parameters of heart rate turbulence

The studies aimed at evaluation of cigarette smoke effect on heart rate turbulence (HRT) in patients with arterial hypertension (AH). 223 consecutive individuals were qualified to the studies. The following groups of patients not suffering from other disease which may affect HRT were distinguished: 1--patients with AH (n=145); 2--patients without AH (n=48). In group 1 the following patient subgroups were studied: A--active smokers (n=42), B--non-smokers exposed to cigarette smoke (n=30), C--non-smokers not exposed to tobacco smoke (n=34), D--former smokers who had quit smoking (n=26). In every participant HRT analysis was conducted. Subgroup A manifested significantly higher values of TO and lower values of TS as compared to analogous values obtained in subgroups B-D. Subgroups B and D were characterized also by significantly higher values of TO and lower values of TS as compared to subgroup C. Active and passive cigarette smoking were found to represent independent risk factors for an abnormal HRT.

CONCLUSION

Both active and passive exposure to tobacco smoke induces causes abnormal HRT in patients with arterial hypertension.

Symptoms of disturbed sleep predict major adverse cardiac events after percutaneous coronary intervention

BACKGROUND

Disturbed sleep is associated with atherosclerosis in native coronary arteries and may be associated with adverse cardiac events after percutaneous coronary intervention (PCI). We sought to determine the association between symptoms of disturbed sleep and adverse cardiovascular events after PCI.

METHODS

Outpatients who were stable after successful PCI were assessed for symptoms of disturbed sleep with 10 true/false questions. Follow-up was performed at least 4 years after PCI. The primary outcome was a composite of death, myocardial infarction (MI), and repeated revascularization.

RESULTS

Three hundred eighty-eight patients (mean age, 66 ± 11 years) reported on average 3.1 ± 2.1 sleep disturbance symptoms. Follow-up was performed on average 4.4 years after the incident PCI. The primary outcome occurred in 25% of patients. An association was seen between the number of sleep disturbance symptoms and the occurrence of the primary end point. Patients with zero symptoms had a 4-year event rate of 12% compared with a 67% event rate for those with 9 symptoms. On multivariable analysis, sleep symptoms, diabetes mellitus, and the number of diseased coronary vessels were independently associated with the primary end point. Each additional sleep symptom was associated with a hazard ratio (HR) of 1.2 (P = 0.001). The results were driven primarily by the association between symptoms of disturbed sleep and the need for repeated revascularization (repeated PCI HR, 1.9; P = 0.003; coronary artery bypass grafting (CABG) HR, 1.5; P = 0.001).

CONCLUSIONS

Symptoms of disturbed sleep were associated with increased risk of long-term adverse cardiovascular outcomes after successful PCI.

Electrocardiologic and related methods of non-invasive detection and risk stratification in myocardial ischemia: state of the art and perspectives

Background: Electrocardiographic methods still provide the bulk of cardiovascular diagnostics. Cardiac ischemia is associated with typical alterations in cardiac biosignals that have to be measured, analyzed by mathematical algorithms and allegorized for further clinical diagnostics. The fast growing fields of biomedical engineering and applied sciences are intensely focused on generating new approaches to cardiac biosignal analysis for diagnosis and risk stratification in myocardial ischemia.

Objectives: To present and review the state of the art in and new approaches to electrocardiologic methods for non-invasive detection and risk stratification in coronary artery disease (CAD) and myocardial ischemia; secondarily, to explore the future perspectives of these methods.

Methods: In follow-up to the Expert Discussion at the 2008 Workshop on "Biosignal Analysis" of the German Society of Biomedical Engineering in Potsdam, Germany, we comprehensively searched the pertinent literature and databases and compiled the results into this review. Then, we categorized the state-of-the-art methods and selected new approaches based on their applications in detection and risk stratification of myocardial ischemia. Finally, we compared the pros and cons of the methods and explored their future potentials for cardiology.

Results: Resting ECG, particularly suited for detecting ST-elevation myocardial infarctions, and exercise ECG, for the diagnosis of stable CAD, are state-of-the-art methods. New exercise-free methods for detecting stable CAD include cardiogoniometry (CGM); methods for detecting acute coronary syndrome without ST elevation are Body Surface Potential Mapping, functional imaging and CGM. Heart rate variability and blood pressure variability analyses, microvolt T-wave alternans and signal-averaged ECG mainly serve in detecting and stratifying the risk for lethal arrythmias in patients with myocardial ischemia or previous myocardial infarctions. Telemedicine and ambient-assisted living support the electrocardiological monitoring of at-risk patients.

Conclusions: There are many promising methods for the exercise-free, non-invasive detection of CAD and myocardial ischemia in the stable and acute phases. In the coming years, these new methods will help enhance state-of-the-art procedures in routine diagnostics. The future can expect that equally novel methods for risk stratification and telemedicine will transition into clinical routine.

Heart rate turbulence: standards of measurement, physiological interpretation, and clinical use: International Society for Holter and Noninvasive Electrophysiology Consensus

This consensus statement has been compiled on behalf of the International Society for Holter and Noninvasive Electrophysiology. It reviews the topic of heart rate turbulence (HRT) and concentrates on technologies for measurement, physiologic background and interpretation, and clinical use of HRT. It also lists suggestions for future research. The phenomenon of HRT refers to sinus rhythm cycle-length perturbations after isolated premature ventricular complexes. The physiologic pattern of HRT consists of brief heart rate acceleration (quantified by the so-called turbulence onset) followed by more gradual heart rate deceleration (quantified by the so-called turbulence slope) before the rate returns to a pre-ectopic level. Available physiologic investigations confirm that the initial heart rate acceleration is triggered by transient vagal inhibition in response to the missed baroreflex afferent input caused by hemodynamically inefficient ventricular contraction. A sympathetically mediated overshoot of arterial pressure is responsible for the subsequent heart rate deceleration through vagal recruitment. Hence, the HRT pattern is blunted in patients with reduced baroreflex. The HRT pattern is influenced by a number of factors, provocations, treatments, and pathologies reviewed in this consensus. As HRT measurement provides an indirect assessment of baroreflex, it is useful in those clinical situations that benefit from baroreflex evaluation. The HRT evaluation has thus been found appropriate in risk stratification after acute myocardial infarction, risk prediction, and monitoring of disease progression in heart failure, as well as in several other pathologies.

Autonomic cardiac control with xenon anaesthesia in patients at cardiovascular risk

BACKGROUND

The cardiovascular stability found with xenon anaesthesia may be caused by absence of circulatory depression. Xenon may also act directly on autonomic cardiovascular control.

METHODS

In a prospective, randomized design, 26 patients (ASA class III and IV) with increased cardiac risk were anaesthetized for elective non-cardiac surgery with either xenon (n = 13) or propofol (n = 13), each combined with remifentanil. From intraoperative Holter ECG, 5-min intervals of stable sinus rhythm were analysed at baseline anaesthesia with etomidate/remifentanil, and after 30 and 60 min of propofol or xenon anaesthesia. Target criteria were total power and ratio of low to high frequency power of the heart rate (HR) power spectrum between 0.003 and 0.4 Hz, indicating global activity and sympatho-vagal balance of autonomic modulation of HR.

RESULTS

When compared with baseline, total power decreased with propofol from 8.6 (1.6) to 7.1 (0.5) and to 7.8 (1.1) ms(2) at 30 and 60 min, respectively, [mean (sd) of logarithmic transform] and was unchanged with xenon (P = 0.02; anova). The low/high frequency power ratio changed from 3.0 (3.5) to 4.3 (4.3) and 4.1 (6.2), respectively, with xenon and from 3.9 (3.6) to 1.8 (1.5) and 1.8 (0.8) with propofol (P = 0.04; generalized linear model test). Mean arterial pressure was significantly higher with xenon throughout (P < 0.001; anova).

CONCLUSIONS

Propofol caused a decrease in arterial pressure as well as autonomic HR modulation, but xenon did not. The higher arterial pressure with xenon anaesthesia may be explained by less suppression of sympatho-vagal balance.