Ejection Fraction In Sinus Rhythm Research Articles

Atrial secondary tricuspid regurgitation: pathophysiology, definition, diagnosis, and treatment.

Atrial secondary tricuspid regurgitation (A-STR) is a distinct phenotype of secondary tricuspid regurgitation with predominant dilation of the right atrium and normal right and left ventricular function. Atrial secondary tricuspid regurgitation occurs most commonly in elderly women with atrial fibrillation and in heart failure with preserved ejection fraction in sinus rhythm. In A-STR, the main mechanism of leaflet malcoaptation is related to the presence of a significant dilation of the tricuspid annulus secondary to right atrial enlargement. In addition, there is an insufficient adaptive growth of tricuspid valve leaflets that become unable to cover the enlarged annular area. As opposed to the ventricular phenotype, in A-STR, the tricuspid valve leaflet tethering is typically trivial. The A-STR phenotype accounts for 10%-15% of clinically relevant tricuspid regurgitation and has better outcomes compared with the more prevalent ventricular phenotype. Recent data suggest that patients with A-STR may benefit from more aggressive rhythm control and timely valve interventions. However, little is mentioned in current guidelines on how to identify, evaluate, and manage these patients due to the lack of consistent evidence and variable definitions of this entity in recent investigations. This interdisciplinary expert opinion document focusing on A-STR is intended to help physicians understand this complex and rapidly evolving topic by reviewing its distinct pathophysiology, diagnosis, and multi-modality imaging characteristics. It first defines A-STR by proposing specific quantitative criteria for defining the atrial phenotype and for discriminating it from the ventricular phenotype, in order to facilitate standardization and consistency in research.

Efficacy of Dapagliflozin According to Heart Rate: A Patient-Level Pooled Analysis of DAPA-HF and DELIVER.

Although elevated resting heart rate (HR) is associated with a higher risk of cardiovascular events in patients with heart failure with reduced ejection fraction in sinus rhythm (SR), the relationship between HR and outcomes among patients with heart failure with mildly reduced ejection fraction/heart failure with preserved ejection fraction and in those with atrial fibrillation (AF) is uncertain. The aims of this study were to examine the association between baseline HR and outcomes across the range of left ventricular ejection fraction, in patients with and without AF, and evaluate the effect of dapagliflozin according to HR. A patient-level pooled analysis of the DAPA-HF (Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure; heart failure with reduced ejection fraction) and DELIVER (Dapagliflozin Evaluation to Improve the Lives of Patients With Preserved Ejection Fraction Heart Failure trial; heart failure with mildly reduced ejection fraction/heart failure with preserved ejection fraction) trials. The primary outcome of each was the composite of worsening heart failure or cardiovascular death. Among patients with SR (n=6401, 64%), the rate of the primary outcome was higher in those with higher HR: 16.8 versus 7.7 per 100 person-years for ≥80 bpm versus <60 bpm. The relationship between HR and risk was steeper in heart failure with reduced ejection fraction versus heart failure with mildly reduced ejection fraction/heart failure with preserved ejection fraction. HR was not associated with outcomes in patients in AF for either heart failure phenotype. The benefit of dapagliflozin on the primary outcome was consistent across the HR range in both SR (Pinteraction=0.28) and AF (Pinteraction=0.56), for example, for SR <60 bpm, hazard ratio for dapagliflozin versus placebo 0.72 (95% CI, 0.55-0.95); 60 to 69 bpm, 0.78 (0.63-0.97); 70 to 79 bpm, 0.73 (0.59-0.91); ≥80 bpm, 0.77 (0.61-0.97). The benefit was consistent across HR range in both heart failure with reduced ejection fraction and heart failure with mildly reduced ejection fraction/heart failure with preserved ejection fraction. The risk of worsening heart failure or cardiovascular death increased with increasing baseline HR among patients in SR, but this association was not seen among patients in AF, irrespective of left ventricular ejection fraction. The benefit of dapagliflozin was consistent across HR range, irrespective of left ventricular ejection fraction or rhythm. URL: https://www.clinicaltrials.gov; Unique identifiers: NCT03036124 and NCT03619213.

Prognostic impact of left atrial function in heart failure with preserved ejection fraction in sinus rhythm vs. persistent atrial fibrillation.

AimsWe sought to determine the prognostic impact of left atrial (LA) size and function in patients with heart failure with preserved ejection fraction (HFpEF) in sinus rhythm (SR) vs. atrial fibrillation (AF).Methods and resultsWe enrolled consecutive HFpEF patients and assessed indexed LA volumes and emptying fractions (LA‐EF) on cardiac magnetic resonance imaging. In addition, all patients underwent right and left heart catheterization, 6 min walk test, and N‐terminal prohormone of brain natriuretic peptide evaluation. We prospectively followed patients and used Cox regression models to determine the association of LA size and function with a composite endpoint of heart failure hospitalization and cardiovascular death. A total of 188 patients (71% female patients, 70 ± 8 years old) were included of whom 92 (49%) were in persistent AF. Sixty‐five patients reached the combined endpoint during a follow‐up of 31 (9–57) months. Multivariate Cox regression adjusted for established risk factors revealed that LA‐EF was significantly associated with outcome in patients in SR [adjusted hazard ratio 2.14; 95% confidence interval (1.32–3.47) per 1‐SD decline, P = 0.002]. In persistent AF, no LA imaging parameter was related to outcome. By receiver operating characteristic and restricted cubic spline analyses, we identified an LA‐EF ≥ 40% as best indicator for favourable outcomes in patients with HFpEF and SR. Persistent AF carried a similar risk for adverse outcome compared with impaired LA‐EF (<40%) in SR (log‐rank, P = 0.340).ConclusionsIn HFpEF patients in SR, impaired LA‐EF is independently associated with worse cardiovascular outcome, which is similar to persistent AF. In persistent AF, LA parameters lose their prognostic ability.

Prognostic impact of left atrial function in heart failure with preserved ejection fraction in sinus rhythm vs. atrial fibrillation

Abstract Background Left atrial (LA) function is related with outcome in heart failure with preserved ejection fraction (HFpEF). However, how LA function contributes to outcome in the context of atrial fibrillation (AF) versus sinus rhythm (SR) remains unclear. Purpose To determine the prognostic impact of LA size and phasic function in patients with HFpEF in SR vs. AF. Methods We enrolled consecutive HFpEF patients and assessed indexed LA volumes (LAVi) and emptying fractions (LA-EF) on cardiac magnetic resonance (CMR) imaging. We prospectively followed patients and used Cox regression models to determine the association of LA size and function with a composite endpoint of heart failure hospitalization and cardiovascular death. Results A total of 188 patients (71% female, 70±8 y/o) were included of whom 92 (49%) were in persistent AF (Figure 1A). Patients in persistent AF were older (p=0.017) and had a worse NYHA functional class (p=0.003). Compared to SR, peak and minimal LAVi were increased and LA-EF impaired (each p&amp;lt;0.001 respectively) in persistent AF patients (Figure 2A). A total of 65 patients reached the combined endpoint during a follow-up of 31 (9–57) months. Multivariate Cox regression adjusted for established risk factors revealed that LA-EF was significantly associated with outcome in patients in SR (adj.HR 2.14; 95% CI [1.32–3.47] per 1-SD decline, p=0.002). In persistent AF, however, no LA imaging parameter was related to outcome (Figure 1B). By receiver operating characteristic curve and restricted cubic spline- analyses, we identified an LA-EF ≥40% as best indicator for favorable outcomes in patients with HFpEF and SR (Figure 2B). Persistent AF carried a similar risk for adverse outcome compared to impaired LA-EF (&amp;lt;40%) in SR (log-rank, p=0.340) (Figure 1A). Conclusions In HFpEF patients in SR, impaired LA-EF is independently associated with worse cardiovascular outcome, which is similar to persistent AF. With disease progression including development of persistent AF, LA parameters lose their prognostic ability and thus, are not helpful for further risk stratification. Funding Acknowledgement Type of funding sources: None. Figure 1Figure 2

Observations on changes in ventricular repolarization following four weeks of exercise training in chronic heart failure patients

Objective The aim of this study was to investigate the effects of exercise training on ventricular repolarization dynamicity and heart rate variability in chronic heart failure patients. Design A total of 22 chronic heart failure patients with reduced ejection fraction in sinus rhythm were included in the study. The patients were in NYHA classes II–III with an ejection fraction of 29.7 ± 7.7%. Before and after 4 weeks of aerobic exercise training, all patients performed a cardiopulmonary exercise test, a standard twelve-lead electrocardiogram and a 24 h Holter recording from which heart rate variability and ventricular repolarization dynamicity were assessed. Results We observed a significant decrease of QTpeak (p < .001) and QTend (p < .001) at RR intervals ranging from 600 to 1000 ms on 24 h QT/RR regressions after 4 weeks of exercise training. Our analyses revealed that short-term exercise training induced significant changes in the frequency and time domain HRV parameters on an overall time-period of 24 h. Conclusion Four weeks of exercise training induced significant changes in ventricular repolarization dynamicity in chronic heart failure patients. In addition, short-term exercise training was enough to improve patients’ heart rate variability.

A comparison of anticoagulation, antiplatelet, and placebo treatment for patients with heart failure reduced ejection fraction in sinus rhythm: a systematic review and meta-analysis.

Previous meta-analyses have not recommended routine warfarin use in heart failure (HF) patients but included limited data on contemporary anticoagulants and practices. We conducted an updated meta-analysis in light of newer literature evaluating rivaroxaban in this patient population. The aim of this meta-analysis was to assess if anticoagulation is associated with a decrease in all-cause mortality, myocardial infarction (MI), stroke, and hospitalization for HF exacerbation without an increased risk of major bleeding. A systematic search was conducted for randomized controlled trials to evaluate the use of antithrombotic therapy in patients with HF in sinus rhythm. Outcomes evaluated included all-cause mortality (ACM), non-fatal stroke, MI, hospitalization for HF exacerbation, and major bleeding. Five trials met criteria with a total of 9390 patients included. Four of the five trials evaluated warfarin use and one trial evaluated rivaroxaban. When anticoagulation was compared to control (antiplatelet and placebo groups), a significant reduction in ischemic stroke was found (OR 0.57; 95% CI, 0.42 to 0.78; P = 0.0005, I2 = 6.9%) and no significant difference was found in the risk of ACM, MI, or HF hospitalization. A significant increase in major bleeding was observed in the anticoagulation group when compared to the control group (OR 2.00; 95% CI, 1.45 to 2.75; P = < 0.0001, I2 = 25.79%). Anticoagulation in HF patients in normal sinus rhythm does not appear to reduce mortality rate, prevent MI, or decrease HF hospitalizations. Use reduces risk of ischemic stroke but is counterbalanced with an increase in major bleeding.

Prognostic significance of changes in heart rate following uptitration of beta-blockers in patients with sub-optimally treated heart failure with reduced ejection fraction in sinus rhythm versus atrial fibrillation

BackgroundIn patients with heart failure with reduced ejection fraction (HFrEF) on sub-optimal doses of beta-blockers, it is conceivable that changes in heart rate following treatment intensification might be important regardless of underlying heart rhythm. We aimed to compare the prognostic significance of both achieved heart rate and change in heart rate following beta-blocker uptitration in patients with HFrEF either in sinus rhythm (SR) or atrial fibrillation (AF).MethodsWe performed a post hoc analysis of the BIOSTAT-CHF study. We evaluated 1548 patients with HFrEF (mean age 67 years, 35% AF). Median follow-up was 21 months. Patients were evaluated at baseline and at 9 months. The combined primary outcome was all-cause mortality and heart failure hospitalisation stratified by heart rhythm and heart rate at baseline.ResultsDespite similar changes in heart rate and beta-blocker dose, a decrease in heart rate at 9 months was associated with reduced incidence of the primary outcome in both SR and AF patients [HR per 10 bpm decrease—SR: 0.83 (0.75–0.91), p < 0.001; AF: 0.89 (0.81–0.98), p = 0.018], whereas the relationship was less strong for achieved heart rate in AF [HR per 10 bpm higher—SR: 1.26 (1.10–1.46), p = 0.001; AF: 1.08 (0.94–1.23), p = 0.18]. Achieved heart rate at 9 months was only prognostically significant in AF patients with high baseline heart rates (p for interaction 0.017 vs. low).ConclusionsFollowing beta-blocker uptitration, both achieved and change in heart rate were prognostically significant regardless of starting heart rate in SR, however, they were only significant in AF patients with high baseline heart rate.

Impact of Increased Right Atrial Size on Long-Term Mortality in Patients With Heart Failure Receiving Cardiac Resynchronization Therapy

The ability to visualize the right atrium (RA) by echocardiography allows a quantitative, highly reproducible assessment of the RA volume (RAV). The aim of this study is to evaluate the relation between RAV and long-term mortality in a prospective cohort of heart failure and reduced ejection fraction patients in sinus rhythm receiving cardiac resynchronization therapy. 172 patients were included. The right atrium volume index (RAVI) was calculated using Simpson's method from the apical four-chamber view and indexed to body surface area. The relation between RAVI and mortality during follow up was studied. Median follow up was 68 months (interquartile range 62 to 73 months). Mean RAVI was 27 ± 14 mL/m² (IQR 22 to 33 mL/m²). Cumulative 5-year all-cause mortality was 22 ± 6% in patients with RAVI ≤ 19 mL/m², 24 ± 6% for RAVI 19 to 29 mL/m² and 58 ± 7% for RAVI >29 mL/m² (p for trend <0.001). After adjustment on clinical and echocardiographic predictors of outcome including indices of right ventricular function, there was a significant increase in overall mortality risk with increasing RAVI (adjusted hazard ratio 1.02 [95% confidence interval, 1.00 to 1.03], per 1 mL/m2 increment; p = 0.042). Patients in the highest tertile (RAVI >29 mL/m²) had significantly greater risk of death compared with those with RAVI ≤29 mL/m² (adjusted hazard ratio 2.01 [95% confidence interval, 1.15 to 3.50]; p = 0.014). In conclusion, RA enlargement is a powerful and highly reproducible independent predictor of long-term mortality in patients with heart failure and reduced ejection fraction in sinus rhythm receiving cardiac resynchronization therapy.

Heart Rate and Rhythm and the Benefit of Beta-Blockers in Patients With Heart Failure

BackgroundThe relationship between mortality and heart rate remains unclear for patients with heart failure with reduced ejection fraction in either sinus rhythm or atrial fibrillation (AF). ObjectivesThis analysis explored the prognostic importance of heart rate in patients with heart failure with reduced ejection fraction in randomized controlled trials comparing beta-blockers and placebo. MethodsThe Beta-Blockers in Heart Failure Collaborative Group performed a meta-analysis of harmonized individual patient data from 11 double-blind randomized controlled trials. The primary outcome was all-cause mortality, analyzed with Cox proportional hazard ratios (HR) modeling heart rate measured at baseline and approximately 6 months post-randomization. ResultsA higher heart rate at baseline was associated with greater all-cause mortality for patients in sinus rhythm (n = 14,166; adjusted HR: 1.11 per 10 beats/min; 95% confidence interval [CI]: 1.07 to 1.15; p < 0.0001) but not in AF (n = 3,034; HR: 1.03 per 10 beats/min; 95% CI: 0.97 to 1.08; p = 0.38). Beta-blockers reduced ventricular rate by 12 beats/min in both sinus rhythm and AF. Mortality was lower for patients in sinus rhythm randomized to beta-blockers (HR: 0.73 vs. placebo; 95% CI: 0.67 to 0.79; p < 0.001), regardless of baseline heart rate (interaction p = 0.35). Beta-blockers had no effect on mortality in patients with AF (HR: 0.96, 95% CI: 0.81 to 1.12; p = 0.58) at any heart rate (interaction p = 0.48). A lower achieved resting heart rate, irrespective of treatment, was associated with better prognosis only for patients in sinus rhythm (HR: 1.16 per 10 beats/min increase, 95% CI: 1.11 to 1.22; p < 0.0001). ConclusionsRegardless of pre-treatment heart rate, beta-blockers reduce mortality in patients with heart failure with reduced ejection fraction in sinus rhythm. Achieving a lower heart rate is associated with better prognosis, but only for those in sinus rhythm.

The Prognostic Significance of Heart Rate in Patients Hospitalized for Heart Failure With Reduced Ejection Fraction in Sinus Rhythm: Insights From the EVEREST (Efficacy of Vasopressin Antagonism in Heart Failure: Outcome Study With Tolvaptan) Trial

The purpose of this study was to characterize the relationship between heart rate and post-discharge outcomes in patients with hospitalization for heart failure (HHF) with reduced ejection fraction (EF) in sinus rhythm. A reduction in heart rate improves clinical outcomes in patients with chronic heart failure and in sinus rhythm, but the association between heart rate and post-discharge outcomes in patients with HHF is presently unclear. This post-hoc analysis of the EVEREST (Efficacy of Vasopressin Antagonism in Heart Failure: Outcome Study With Tolvaptan) trial examined 1,947 patients with HHF and EF≤40% not in atrial fibrillation/flutter or pacemaker dependent. The median follow-up period was 9.9 months. At baseline, patients with a higher heart rate tended to be younger with lower EF and were more likely to have worse New York Heart Association functional class and higher natriuretic peptide levels. After adjustment for clinical risk factors, baseline heart rate was not predictive of all-cause mortality (p≥ 0.066). However, at≥70 beats/min, every 5-beat increase in 1-week post-discharge heart rate was independently associated with increased all-cause mortality (hazard ratio: 1.13 [95% confidence interval: 1.05 to 1.22]; p= 0.002). Similarly, every 5-beat increase≥70 beats/min in 4-week post-discharge heart rate was predictive of all-cause mortality (hazard ratio: 1.12 [95% confidence interval: 1.05 to 1.19]; p= 0.001). In this large cohort of patients with HHF with reduced EF and in sinus rhythm, baseline heart rate did not correlate with all-cause mortality. In contrast, at≥70 beats/min, higher heart rate in the early post-discharge period was independently predictive of death during subsequent follow-up. Further study of post-discharge heart rate as a potential therapeutic target in this high-risk population is encouraged.

Benefit of Warfarin Compared With Aspirin in Patients With Heart Failure in Sinus Rhythm

Background— The Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction (WARCEF) trial found no difference in the primary outcome between warfarin and aspirin in 2305 patients with reduced left ventricular ejection fraction in sinus rhythm. However, it is unknown whether any subgroups benefit from warfarin or aspirin. Methods and Results— We used a Cox model stepwise selection procedure to identify subgroups that may benefit from warfarin or aspirin on the WARCEF primary outcome. A secondary analysis added major hemorrhage to the outcome. The primary efficacy outcome was time to the first to occur of ischemic stroke, intracerebral hemorrhage, or death. Only age group was a significant treatment effect modifier ( P for interaction, 0.003). Younger patients benefited from warfarin over aspirin on the primary outcome (4.81 versus 6.76 events per 100 patient-years: hazard ratio, 0.63; 95% confidence interval, 0.48–0.84; P =0.001). In older patients, therapies did not differ (9.91 versus 9.01 events per 100 patient-years: hazard ratio, 1.09; 95% confidence interval, 0.88–1.35; P =0.44). With major hemorrhage added, in younger patients the event rate remained lower for warfarin than aspirin (5.41 versus 7.25 per 100 patient-years: hazard ratio, 0.68; 95% confidence interval, 0.52–0.89; P =0.005), but in older patients it became significantly higher for warfarin (11.80 versus 9.35 per 100 patient-years: hazard ratio, 1.25; 95% confidence interval, 1.02–1.53; P =0.03). Conclusions— In patients &lt;60 years, warfarin improved outcomes over aspirin with or without inclusion of major hemorrhage. In patients ≥60 years, there was no treatment difference, but the aspirin group had significantly better outcomes when major hemorrhage was included. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00041938.

Stroke in Heart Failure in Sinus Rhythm: The Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction Trial

Background: The Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction trial found no difference between warfarin and aspirin in patients with low ejection fraction in sinus rhythm for the primary outcome: first to occur of 84 incident ischemic strokes (IIS), 7 intracerebral hemorrhages or 531 deaths. Prespecified secondary analysis showed a 48% hazard ratio reduction (p = 0.005) for warfarin in IIS. Cardioembolism is likely the main pathogenesis of stroke in heart failure. We examined the IIS benefit for warfarin in more detail in post hoc secondary analyses. Methods: We subtyped IIS into definite, possible and noncardioembolic using the Stroke Prevention in Atrial Fibrillation method. Statistical tests, stratified by prior ischemic stroke or transient ischemic attack, were the conditional binomial for independent Poisson variables for rates, the Cochran-Mantel-Haenszel test for stroke subtype and the van Elteren test for modified Rankin Score (mRS) and National Institute of Health Stroke Scale (NIHSS) distributions, and an exact test for proportions. Results: Twenty-nine of 1,142 warfarin and 55 of 1,163 aspirin patients had IIS. The warfarin IIS rate (0.727/100 patient-years, PY) was lower than for aspirin (1.36/100 PY, p = 0.003). Definite cardioembolic IIS was less frequent on warfarin than aspirin (0.22 vs. 0.55/100 PY, p = 0.012). Possible cardioembolic IIS tended to be less frequent on warfarin than aspirin (0.37 vs. 0.67/100 PY, p = 0.063) but noncardioembolic IIS showed no difference: 5 (0.12/100 PY) versus 6 (0.15/100 PY, p = 0.768). Among patients experiencing IIS, there were no differences by treatment arm in fatal IIS, baseline mRS, mRS 90 days after IIS, and change from baseline to post-IIS mRS. The warfarin arm showed a trend to a lower proportion of severe nonfatal IIS [mRS 3-5; 3/23 (13.0%) vs. 16/48 (33.3%), p = 0.086]. There was no difference in NIHSS at the time of stroke (p = 0.825) or in post-IIS mRS (p = 0.948) between cardioembolic, possible cardioembolic and noncardioembolic stroke including both warfarin and aspirin groups. Conclusions: The observed benefits in the reduction of IIS for warfarin compared to aspirin are most significant for cardioembolic IIS among patients with low ejection fraction in sinus rhythm. This is supported by trends to lower frequencies of severe IIS and possible cardioembolic IIS in patients on warfarin compared to aspirin.

Effect of Electrophysiological Testing on Ejection Fraction During Cardioverter/Defibrillator Implantation

To evaluate the effect of repeated induction of ventricular tachycardia or ventricular fibrillation, or both, in patients with poor left ventricular function, we performed intraoperative two-dimensional echocardiography in 6 patients undergoing implantation of the automatic implantable cardioverter/defibrillator. Changes in left ventricular ejection fraction in sinus rhythm were assessed before the first inducible ventricular arrhythmia and after a mean of 6 ± 1.9 (SD) episodes of ventricular tachycardia or ventricular fibrillation. During the procedure no significant change in mean ejection fraction was observed (28 ± 14 versus 27 ± 17%). Only 1 of the 6 patients studied had a change in ejection fraction greater than 3% (a decrease from 20 to 11%). In an overall clinical series of 38 primary implants or generator changes (including electrophysiological testing) in 29 patients, 1 patient recovered after postoperative inotropic support and 1 died of acute postoperative ischemic heart failure. We conclude that ventricular arrhythmias induced during automatic implantable cardioverter/defibrillator implantation have no immediate deleterious effects on ejection fraction in most patients with compromised left ventricular function and without ongoing ischemia.

Two-dimensional echocardiographic studies during sustained ventricular tachycardia.

We evaluated left ventricular function in patients with recurrent sustained ventricular tachycardia (VT) using two-dimensional echocardiography (2DE). Thirteen patients, 11 men and 2 women, age range 42-77 (mean 62 +/- 12) years were studied in sinus rhythm (SR) and immediately after VT induction. 2DE parameters analyzed included wall motion, mitral valve leaflet motion, and ejection fraction (EF). In SR, 21 segments/walls in 12 patients showed wall motion abnormalities (WMA) ranging from hypokinesis to dyskinesis and one patient had generalized LV hypokinesis. In VT, new WMA were noted in 2 patients. Thirteen segments/walls in 8 patients showed further worsening of pre-existing WMA. In 1 patient there was worsening of generalized LV hypokinesis. Three patients showed apparent improvement in pre-existing WMA during VT. In 2 patients large apical aneurysms showed a reduction of dyskinesis in VT. Mitral valve opening was intermittent in patients with shorter VT cycle lengths and was maximal when atrial systole preceded or coincided with ventricular depolarization. Doppler echocardiography in 1 patient confirmed the pattern of intermittent mitral flow, with greatest flow occurring when mitral valve opening occurred well before the QRS peak. In 5 patients, 2DE permitted EF measurements. EF in SR ranged from 24-56% (mean 36 +/- 13), decreased to 6-33% (mean 21 +/- 11) within the first ten beats of VT and 6-25% (mean 19 +/- 8) after twenty beats of VT. EF decreased more in patients with shorter VT cycles as compared to those with longer VT cycle lengths.(ABSTRACT TRUNCATED AT 250 WORDS)