Mechanisms Underlying QT Interval Adaptation Behind Heart Rate During Stress Test

Abstract Background Targeted hypothermia, as used after cardiac arrest, increases electrical and mechanical systolic duration. Differences in duration of electrical and mechanical systole are correlated to ventricular arrhythmias. The electromechanical window (EMW) becomes negative when the electrical systole outlasts the mechanical systole. Prolonged electrical systole corresponds to prolonged QT interval, and is associated with increased dispersion of repolarization and mechanical dispersion. These three factors predispose for arrhythmias. The electromechanical relations during targeted hypothermia are unknown. We wanted to explore the electromechanical relations during hypothermia at 33 °C. We hypothesized that targeted hypothermia would increase electrical and mechanical systolic duration without more profound EMW negativity, nor an increase in dispersion of repolarization and mechanical dispersion. Methods In a porcine model (n = 14), we registered electrocardiogram (ECG) and echocardiographic recordings during 38 °C and 33 °C, at spontaneous and atrial paced heart rate 100 beats/min. EMW was calculated by subtracting electrical systole; QT interval, from the corresponding mechanical systole; QRS onset to aortic valve closure. Dispersion of repolarization was measured as time from peak to end of the ECG T wave. Mechanical dispersion was calculated by strain echocardiography as standard deviation of time to peak strain. Results Electrical systole increased during hypothermia at spontaneous heart rate (p < 0.001) and heart rate 100 beats/min (p = 0.005). Mechanical systolic duration was prolonged and outlasted electrical systole independently of heart rate (p < 0.001). EMW changed from negative to positive value (− 20 ± 19 to 27 ± 34 ms, p = 0.001). The positivity was even more pronounced at heart rate 100 beats/min (− 25 ± 26 to 41 ± 18 ms, p < 0.001). Dispersion of repolarization decreased (p = 0.027 and p = 0.003), while mechanical dispersion did not differ (p = 0.078 and p = 0.297). Conclusion Targeted hypothermia increased electrical and mechanical systolic duration, the electromechanical window became positive, dispersion of repolarization was slightly reduced and mechanical dispersion was unchanged. These alterations may have clinical importance. Further clinical studies are required to clarify whether corresponding electromechanical alterations are accommodating in humans.

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Electrocardiographic characteristics and associated outcomes in patients with Takotsubo syndrome. Insights from the RETAKO registry

European Heart Journal ◽

10.1093/ehjci/ehaa946.1816 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

I Martin-Demiguel ◽

I Nunez-Gil ◽

A Perez-Castellanos ◽

O Vedia ◽

A Uribarri ◽

...

Keyword(s):

Heart Rate ◽

Primary Endpoint ◽

Qt Interval ◽

Protective Factor ◽

Independent Predictor ◽

Prognostic Significance ◽

Takotsubo Syndrome ◽

St Segment Elevation ◽

Corrected Qt Interval ◽

St Segment

Abstract Background Our aim was to describe the prevalence and prognostic significance of electrocardiographic features in patients with Takotsubo syndrome (TTS). Methods Our data come from the Spanish Multicenter REgistry of TAKOtsubo syndrome (RETAKO). All patients with complete electrocardiogram were included. Results 246 patients were studied, mean age was 71.3±11.5 and 215 (87.4%) were women. ST-segment elevation was seen in 143 patients (59.1%) and was present in ≥2 wall leads in 97 (39.8%). Exclusive elevation in inferior leads was infrequent (5 - 2.0%). After 48 hours, 198 patients (88.0%) developed negative T-waves in a median of 8 leads with a mean amplitude of 0.7±0.5 mV. Mean corrected QT interval was 520±72 ms and it was independently associated with the primary endpoint of all-cause death and nonfatal cardiovascular events (p=0.002) and all-cause death (p=0.008). A higher heart rate at admission was also an independent predictor of the primary endpoint (p=0.001) and of developing acute pulmonary edema (p=0.04). ST-segment elevation with reciprocal depression was an independent predictor of all-cause death (p=0.04). Absence of ST-segment deviation was a protective factor (p=0.005) for the primary endpoint. Arrhythmias were independently associated with cardiogenic shock (p<0.001). Conclusion Prolonged corrected QT interval, arrhythmia, heart rate at admission and broader repolarization alterations are associated with a poor outcome in TTS. Typical ECG at admission and after 48h. Funding Acknowledgement Type of funding source: None

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Safety and effectiveness of drug therapy for the acutely agitated patient (Part I)

Italian Journal of Medicine ◽

10.4081/itjm.2010.127 ◽

2013 ◽

pp. 127-136

Author(s):

Gianluca Airoldi

Keyword(s):

Heart Rate ◽

Qt Interval ◽

Physical Restraint ◽

Safety Data ◽

Surrogate Marker ◽

Diagnostic Procedures ◽

Torsades De Pointes ◽

Long Qt ◽

Drug Induced ◽

Qt Interval Prolongation

Acute agitation occurs in a variety of medical and psychiatric conditions, and the management of agitated, abusive, or violent patients is a common problem in the emergency department. Rapid control of potentially dangerous behaviors by physical restraint and pharmacologic tranquillization is crucial to ensure the safety of the patient and health-care personnel and to allow diagnostic procedures and treatment of the underlying condition. The purpose of this article (the first in a 2-part series) is to review the extensive safety data published on the antipsychotic medications currently available for managing situations of this type, including older neuroleptics like haloperidol, chlorpromazine, and pimozide as well as a number of the newer atypical antipsychotics (olanzapine, risperidone, ziprasidone). Particular attention is focused on the ability of these drugs to lengthen the QT interval in surface electrocardiograms. This adverse effect is of major concern, especially in light of the reported relation between QT interval and the risk of sudden death. In patients with the congenital long-QT syndrome, a long QT interval is associated with a fatal paroxysmal ventricular arrhythmia knownas torsades de pointes. Therefore, careful evaluation of the QT-prolonging properties and arrhythmogenic potential of antipsychotic drugs is urgently needed. Clinical assessment of drug-induced QT-interval prolongation is strictly dependent on the quality of electrocardiographic data and the appropriateness of electrocardiographic analyses. Unfortunately, measurement imprecision and natural variability preclude a simple use of the actually measured QT interval as a surrogate marker of drug-induced proarrhythmia. Because the QT interval changes with heart rate, a rate-corrected QT interval (QTc) is commonly used when evaluating a drug’s effect. In clinical settings, themost widely used formulas for rate-correction are those of Bazett (QTc=QT/RR^0.5) and Fridericia (QTc=QT/RR^0.33), both of which standardize themeasuredQTinterval to an RRinterval of 1 s (heart rate of 60 bpm).However, QT variability can also be influenced by other factors that are more difficult to measure, including body fat, meals, psycho-physical distress, and circadian and seasonal fluctuations.

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Influence of a Suggestive Placebo Intervention on Psychobiological Responses to Social Stress

Journal of Evidence-Based Complementary & Alternative Medicine ◽

10.1177/2156587215588642 ◽

2015 ◽

Vol 21 (1) ◽

pp. 3-9 ◽

Cited By ~ 1

Author(s):

Frank Zimmermann-Viehoff ◽

Nico Steckhan ◽

Karin Meissner ◽

Hans-Christian Deter ◽

Clemens Kirschbaum

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Salivary Cortisol ◽

Psychosocial Stress ◽

Social Stress ◽

Stress Test ◽

Alpha Amylase ◽

Subjective Stress ◽

Psychological Variables ◽

Placebo Intervention

We tested the hypothesis that a suggestive placebo intervention can reduce the subjective and neurobiological stress response to psychosocial stress. Fifty-four healthy male subjects with elevated levels of trait anxiety were randomly assigned in a 4:4:1 fashion to receive either no treatment (n = 24), a placebo pill (n = 24), or a herbal drug (n = 6) before undergoing a stress test. We repeatedly measured psychological variables as well as salivary cortisol, alpha-amylase, and heart rate variability prior to and following the stress test. The stressor increased subjective stress and anxiety, salivary cortisol, and alpha-amylase, and decreased heart rate variability (all P < .001). However, no significant differences between subjects receiving placebo or no treatment were found. Subjects receiving placebo showed increased wakefulness during the stress test compared with no-treatment controls ( P < .001). Thus, the suggestive placebo intervention increased alertness, but modulated neither subjective stress and anxiety nor the physiological response to psychosocial stress.

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Relation between heart rate and QT interval in exercise-induced myocardial ischemia

The American Journal of Cardiology ◽

10.1016/0002-9149(85)90770-2 ◽

1985 ◽

Vol 56 (13) ◽

pp. 861-862 ◽

Cited By ~ 25

Author(s):

Massimo Romano ◽

Teresa Di Maro ◽

Giovanni Carella ◽

Maria Rosaria Cotecchia ◽

Giuseppe Ferro ◽

...

Keyword(s):

Heart Rate ◽

Myocardial Ischemia ◽

Qt Interval ◽

Exercise Induced

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Abstract 17288: Risk Prediction of 10-Year Cardiovascular Mortality Using Automated Electrocardiographic Analysis in the National Health and Nutrition Examination Survey

Circulation ◽

10.1161/circ.130.suppl_2.17288 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Amit J Shah ◽

Cecile Janssens ◽

Suman Kundu ◽

Emir Veledar ◽

Peter Wilson ◽

...

Keyword(s):

Heart Rate ◽

Risk Prediction ◽

Risk Score ◽

Qt Interval ◽

Validation Cohort ◽

Risk Scores ◽

Older Individuals ◽

Traditional Risk Factors ◽

Ecg Score ◽

Cvd Mortality

Introduction: Several individual ECG parameters are predictive of cardiovascular disease (CVD) mortality, and when combined in a score, may improve risk prediction. Hypothesis: We hypothesized that an ECG risk score (based on automated measures available on many modern ECG machines) can effectively predict CVD mortality, and augment risk classification when added to traditional risk factors (TRF). Methods: We examined 6786 individuals aged 40-79 years without known CVD in NHANES III (1988-1994) followed 10 years for CVD mortality. Six pre-specified ECG variables (“ECG model”), were evaluated including P, R, T axes, QT interval, QRS width, and heart rate. Three risk scores were developed for variables containing: 1) TRF only, 2) ECG factors (including age, sex, and race), and 3) TRF+ECG combined. Validation was performed using a cohort aged 40-74 years from NHANES I (n=3773), enrolled in 1971-1974. Age stratification was performed with cutoff of 65 years because of increased competing risks in older individuals. Results: During 10 years of follow up, 384 CVD deaths occurred. Frontal QRS-T angle, T-axis, wide QRS interval (cutoff 120 ms), heart rate-corrected QT interval, and heart rate were found to be significant predictors (p<0.05) of CVD death. As per the table, the ECG score had similar performance compared to the TRF score for the subgroup < 65 years of age in the derivation and validation cohorts. The score with combined ECG + TRF had the best performance for those aged < 65 years, and resulted in a net reclassification index of 9% in the validation cohort using cutoffs of 7.5% and 20% for low, intermediate, and high risk categories. In those aged ≥ 65 years, the combined score showed improvement vs. the TRF score in the derivation, but not validation cohort. Conclusion: A risk score based on routinely reported automated ECG variables and TRF predicts risk of 10-year CVD death better than TRF alone in a cohort age < 65 years without known CVD.

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Impaired heart rate recovery may predict radial artery spasm in patients undergoing coronary angiography via radial access

Kosuyolu Heart Journal ◽

10.51645/khj.2021.m202 ◽

2021 ◽

Author(s):

İsmail Gürbak ◽

Arda Güler ◽

Cafer Panç ◽

Ahmet Güner ◽

Mehmet Ertürk

Keyword(s):

Heart Rate ◽

Coronary Angiography ◽

Radial Artery ◽

Autonomic Dysfunction ◽

Heart Rate Recovery ◽

Stress Test ◽

Female Gender ◽

Current Data ◽

Autonomic Nervous System Dysfunction ◽

Procedural Time

Objectives: Radial artery spasm (RAS) is associated with several pathophysiological pathways, including endothelial and autonomic dysfunction, and causes failed coronary interventions. Heart rate recovery (HRR) is a simple measurement of autonomic nervous system dysfunction. We aimed to investigate the relationship between HRR and RAS during coronary angiography (CA) in the present study. Patients and Methods: This study included 167 patients (mean age 54.6 ± 8.2, 131 males) who underwent a treadmill stress test (TST) according to the Bruce protocol before trans-radial CA. HRR in the first minute (HRR1) was calculated as the difference between peak heart rate and heart rate one minute after the TST. Patients were divided into two groups according to the presence of RAS. Results: Among the study population, RAS developed in 26 patients (15.5%). HRR1 and HRR in the third minute (HRR3) were lower in the RAS group. Also, the abnormal HRR1 rate was higher in the RAS group (35.5% vs. 76.9%, p < 0.001). Total procedural time, more than one puncture attempt, more than one catheter use, fluoroscopy time, radiation exposure, contrast volume was higher in the RAS group. Female gender, total procedural time, more than one catheter use, and abnormal HRR1 were independent predictors of RAS. Conclusion: The current data suggest that a significant relationship was found between abnormal HRR1 and RAS. HRR, a simple autonomic dysfunction parameter, can provide additional information regarding the success of radial procedures.

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Abstract 187: Electrocardiographic Heart Rate-corrected Qt Interval And Risk Of Stroke In The REasons For Geographic And Racial Differences In Stroke (REGARDS) Study

Stroke ◽

10.1161/str.43.suppl_1.a187 ◽

2012 ◽

Vol 43 (suppl_1) ◽

Author(s):

Elsayed Z Soliman ◽

George Howard ◽

Mary Cushman ◽

Brett Kissela ◽

...

Keyword(s):

Heart Rate ◽

Racial Differences ◽

Qt Interval ◽

Proportional Hazards ◽

Left Ventricular ◽

Cox Proportional Hazards ◽

Corrected Qt Interval ◽

Cardiovascular Morbidity And Mortality ◽

Increased Risk ◽

Regards Study

Background: Prolongation of heart rate-corrected QT interval (QTc) is a well established predictor of cardiovascular morbidity and mortality. Little is known, however, about the relationship between this simple electrocardiographic (ECG) marker and risk of stroke. Methods: A total of 27,411 participants aged > 45 years without prior stroke from the REasons for Geographic and Racial Differences in Stroke (REGARDS) study were included in this analysis. QTc was calculated using Framingham formula (QTcFram). Stroke cases were identified and adjudicated during an up to 7 years of follow-up (median 2.7 years). Cox proportional hazards analysis was used to estimate the hazard ratios for incident stroke associated with prolonged QTcFram interval (vs. normal) and per 1 standard deviation (SD) increase, separately, in a series of incremental models. Results: The risk of incident stroke in the study participants with baseline prolonged QTcFram was almost 3 times the risk in those with normal QTcFram [HR (95% CI): 2.88 (2.12, 3.92), p<0.0001]. After adjustment for age, race, sex, antihypertensive medication use, systolic blood pressure, current smoking, diabetes, left ventricular hypertrophy, atrial fibrillation, prior cardiovascular disease, QRS duration, warfarin use, and QT-prolonging drugs (full model), the risk of stroke remained significantly high [HR (95% CI): 1.67 (1.16, 2.41), p=0.0060)], and was consistent across several subgroups of REGARDS participants. When the risk of stroke was estimated per 1 SD increase in QTcFram, a 24% increased risk was observed [HR (95% CI): 1.24 (1.16, 1.33), p<0.0001)]. This risk remained significant in the fully adjusted model [HR (95% CI): 1.12 (1.03, 1.21), p=0.0055]. Similar results were obtained when other QTc correction formulas including Hodge’s, Bazett’s and Fridericia’s were used. Conclusions: QTc prolongation is associated with a significantly increased risk of incident stroke independently from known stroke risk factors. In light of our results, examining the risk of stroke associated with QT-prolonging drugs may be warranted.

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