Assessment of Autonomic Function in Cardiovascular Disease Lahiri, Marc K., MD; Kannankeril, Prince J., MD; Goldberger, Jeffrey J., MD, FACC
Journal of the American College of Cardiology,
05/2008, Letnik:
51, Številka:
18
Journal Article
Recenzirano
Odprti dostop
Assessment of Autonomic Function in Cardiovascular Disease: Physiological Basis and Prognostic Implications Marc K. Lahiri, Prince J. Kannankeril, Jeffrey J. Goldberger Certain abnormalities of ...autonomic function in the setting of structural cardiovascular disease have been associated with an adverse prognosis. Various markers of autonomic activity have received increased attention as methods for identifying patients at risk for sudden death. Heart rate, heart rate variability, and heart rate recovery are 3 markers that provide information about different aspects of autonomic effects on the sinus node. Autonomic evaluation during exercise and recovery may be important prognostically, because these are high-risk periods for sudden death, and the autonomic changes that occur with exercise could modulate this high risk.
Abstract Background Beta-blocker therapy after acute myocardial infarction (MI) improves survival. Beta-blocker doses used in clinical practice are often substantially lower than those used in the ...randomized trials establishing their efficacy. Objectives This study evaluated the association of beta-blocker dose with survival after acute MI, hypothesizing that higher dose beta-blocker therapy will be associated with increased survival. Methods A multicenter registry enrolled 7,057 consecutive patients with acute MI. Discharge beta-blocker dose was indexed to the target beta-blocker doses used in randomized clinical trials, grouped as >0% to 12.5%, >12.5% to 25%, >25% to 50%, and >50% of target dose. Follow-up vital status was assessed, with the primary endpoint of time-to-death right-censored at 2 years. Multivariable and propensity score analyses were used to account for group differences. Results Of 6,682 patients with follow-up (median 2.1 years), 91.5% were discharged on a beta-blocker (mean dose 38.1% of the target dose). Lower mortality was observed with all beta-blocker doses (p < 0.0002) versus no beta-blocker therapy. After multivariable adjustment, hazard ratios for 2-year mortality compared with the >50% dose were 0.862 (95% confidence interval CI: 0.677 to 1.098), 0.799 (95% CI: 0.635 to 1.005), and 0.963 (95% CI: 0.765 to 1.213) for the >0% to 12.5%, >12.5% to 25%, and >25% to 50% of target dose groups, respectively. Multivariable analysis with an extended set of covariates and propensity score analysis also demonstrated that higher doses were not associated with better outcome. Conclusions These data do not demonstrate increased survival in patients treated with beta-blocker doses approximating those used in previous randomized clinical trials compared with lower doses. These findings provide the rationale to re-engage in research to establish appropriate beta-blocker dosing after MI to derive optimal benefit from this therapy. (The PACE-MI Registry Study—Outcomes of Beta-blocker Therapy After Myocardial Infarction OBTAIN: NCT00430612 )
Abstract Background The outcomes related to chest pain associated with cocaine use and its burden on healthcare system are not well studied. Methods Data were collected from the Nationwide Inpatient ...Sample (2001 – 2012). Subjects were identified by using the ICD-9-CM codes. Primary outcome was a composite of mortality, myocardial infarction, stroke and cardiac arrest. Results We identified 363,143 admissions for cocaine induced chest pain. Mean age was 44.9 ( + 21.1) years with male predominance. Left heart catheterizations were performed in 6.7%, whereas the frequency of acute MI and percutaneous coronary interventions were 0.69% and 0.22% respectively. The in-hospital mortality was 0.09% and the primary outcome occurred in 1.19% of patients. Statistically significant predictors of primary outcome included female sex (OR=1.16, CI 1.00-1.35, p=0.046), age > 50 years (OR=1.24, CI 1.07-1.43, p=0.004), history of heart failure (OR=1.63, CI 1.37-1.93, p<0.001), supraventricular tachycardia (OR=2.94, CI 1.34-6.42, p=0.007), endocarditis (OR=3.5, CI 1.50-8.18, p=0.004), tobacco use (OR=1.3, CI 1.13-1.49, p<0.001, dyslipidemia (OR=1.5, CI 1.29-1.77, p<0.001), coronary artery disease (OR=2.37, CI 2.03-2.76, p<0.001), and renal failure (OR=1.27, CI 1.08-1.50, p=0.005). The total annual projected economic burden ranged from $155 to $226 million with a cumulative accruement of over $2 billion over a decade. Conclusion Hospital admissions due to chest pain and concomitant cocaine use are associated with very low rates adverse outcomes. For the low risk cohort in whom acute coronary syndrome has been ruled out, hospitalization may not be beneficial and may result in unnecessary cardiac procedures.
Abstract Limited data exist on the safety and physiologic effects of caffeine in patients with known arrhythmias. The studies presented suggest that in most patients with known or suspected ...arrhythmia, caffeine in moderate doses is well tolerated and there is therefore no reason to restrict ingestion of caffeine. A review of the literature is presented.
Objectives The purpose of this study was to provide a meta-analysis to estimate the performance of 12 commonly reported risk stratification tests as predictors of arrhythmic events in patients with ...nonischemic dilated cardiomyopathy. Background Multiple techniques have been assessed as predictors of death due to ventricular tachyarrhythmias/sudden death in patients with nonischemic dilated cardiomyopathy. Methods Forty-five studies enrolling 6,088 patients evaluating the association between arrhythmic events and predictive tests (baroreflex sensitivity, heart rate turbulence, heart rate variability, left ventricular end-diastolic dimension, left ventricular ejection fraction, electrophysiology study, nonsustained ventricular tachycardia, left bundle branch block, signal-averaged electrocardiogram, fragmented QRS, QRS-T angle, and T-wave alternans) were included. Raw event rates were extracted, and meta-analysis was performed using mixed effects methodology. We also used the trim-and-fill method to estimate the influence of missing studies on the results. Results Patients were 52.8 ± 14.5 years of age, and 77% were male. Left ventricular ejection fraction was 30.6 ± 11.4%. Test sensitivities ranged from 28.8% to 91.0%, specificities from 36.2% to 87.1%, and odds ratios from 1.5 to 6.7. Odds ratio was highest for fragmented QRS and TWA (odds ratios: 6.73 and 4.66, 95% confidence intervals: 3.85 to 11.76 and 2.55 to 8.53, respectively) and lowest for QRS duration (odds ratio: 1.51, 95% confidence interval: 1.13 to 2.01). None of the autonomic tests (heart rate variability, heart rate turbulence, baroreflex sensitivity) were significant predictors of arrhythmic outcomes. Accounting for publication bias reduced the odds ratios for the various predictors but did not eliminate the predictive association. Conclusions Techniques incorporating functional parameters, depolarization abnormalities, repolarization abnormalities, and arrhythmic markers provide only modest risk stratification for sudden cardiac death in patients with nonischemic dilated cardiomyopathy. It is likely that combinations of tests will be required to optimize risk stratification in this population.
Background While beta-blockers increase survival in acute coronary syndrome (ACS) patients, the doses used in trials were higher than doses used in practice and recent data do not support an ...advantage of higher doses. We hypothesized that rates of major adverse cardiac events (MACE), all-cause death, myocardial infarction (MI), and stroke is equivalent for patients on low-dose and high-dose beta-blocker. Methods Patients admitted to Intermountain Healthcare with ACS and diagnosed with ≥70% coronary stenosis between 1994 and 2013 were studied (n = 7834). We classified low-dose as ≤25% and high-dose as ≥50% of an equivalent daily dose of 200 mg of metoprolol. Multivariate analyses were used to test association between low-dose vs high-dose beta-blocker dosage and MACE at 0–6 months and 6–24 months. Results 5287 ACS subjects were discharged on beta-blockers (87% low-dose, 12% high-dose and 1% intermediate-dose). The 6-month MACE outcomes rates for the beta-blocker dosage (low vs high) were not equivalent ( P = .18) (hazard ratio HR =0.76; 95% CI: 0.52–1.10). However, subjects on low-dose beta-blocker therapy did have a significantly decreased risk of MI for 0–6 months (HR = 0.53; 95% CI: 0.33–0.86). The rates of MACE events during the 6–24 months after presentation with ACS were equivalent for the two doses ( P = .009; HR = 1.03 95% CI: 0.70–1.50). Conclusions In ACS patients, rates of MACE for high-dose and low-dose beta-blocker doses are similar. These findings question the importance of achieving a high-dose of beta-blocker in ACS patients and highlight the need of further investigation of this clinical question.
Differences in implantable cardioverter defibrillator (ICD) utilization based on insurance status have been described, but little is known about postimplant follow-up patterns associated with ...insurance status and outcomes. We collected demographic, clinical, and device data from 119 consecutive patients presenting with ICD shocks. Insurance status was classified as uninsured/Medicaid (uninsured) or private/Health Maintenance Organization /Medicare (insured). Shock frequencies were analyzed before and after a uniform follow-up pattern was implemented regardless of insurance profile. Uninsured patients were more likely to present with an inappropriate shock (63% vs 40%, p = 0.01), and they were more likely to present with atrial fibrillation (AF) as the shock trigger (37% vs 19%, p = 0.04). Uninsured patients had a longer interval between previous physician contact and index ICD shock (147 ± 167 vs 83 ± 124 days, p = 0.04). Patients were followed for a mean of 521 ± 458 days after being enrolled in a uniform follow-up protocol, and there were no differences in the rate of recurrent shocks based on insurance status. In conclusion, among patients presenting with an ICD shock, underinsured/uninsured patients had significantly longer intervals since previous physician contact and were more likely to present with inappropriate shocks and AF, compared to those with private/Medicare coverage. After the index shock, both groups were followed uniformly, and the differences in rates of inappropriate shocks were mitigated. This observation confirms the importance of regular postimplant follow-up as part of the overall ICD management standard.
As left ventricular ejection fraction (LVEF) may improve, worsen, or remain the same over time, patients' prognosis may also be expected to change because of the change in LVEF, among other factors.
...To evaluate the effect of LVEF change on outcome in the Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation (DEFINITE) trial.
Patients with nonischemic cardiomyopathy with LVEF<36%, history of symptomatic heart failure, and the presence of significant ventricular ectopic activity were enrolled in the DEFINITE trial. Follow-up LVEF measurements were obtained annually in only a minority (17%) of trial participants. This study therefore evaluated survival and arrhythmic end points in patients whose LVEF was reassessed between 90 and 730 days after enrollment.
During the 90-730-day postrandomization period, 187 of 449 (42%) enrolled patients who survived at least 90 days had at least 1 follow-up LVEF measurement; these patients were younger and white; had diabetes, better 6-minute walk test results, and higher BMI; were more likely to have appropriate shocks; and had fewer deaths compared to those without follow-up LVEF measurements. Patients whose LVEF improved had reduced mortality compared to patients whose LVEF decreased (hazard ratio 0.09; 95% confidence interval 0.02-0.39; P = .001). Survival free of appropriate shocks was not significantly related to LVEF improvement during follow-up.
LVEF improvement was associated with improved survival, but not with a significant decrease in appropriate shocks. These data highlight that appropriate caution should be exercised not to extrapolate the positive effect of improved LVEF to the elimination of arrhythmic events.
Traditional mapping of atrial fibrillation (AF) is limited by changing electrogram morphologies and variable cycle lengths.
We tested the hypothesis that morphology recurrence plot analysis would ...identify sites of stable and repeatable electrogram morphology patterns.
AF electrograms recorded from left atrial (LA) and right atrial (RA) sites in 19 patients (10 men; mean age 59 ± 10 years) before AF ablation were analyzed. Morphology recurrence plots for each electrogram recording were created by cross-correlation of each automatically detected activation with every other activation in the recording. A recurrence percentage, the percentage of the most common morphology, and the mean cycle length of activations with the most recurrent morphology were computed.
The morphology recurrence plots commonly showed checkerboard patterns of alternating high and low cross-correlation values, indicating periodic recurrences in morphologies. The mean recurrence percentage for all sites and all patients was 38 ± 25%. The highest recurrence percentage per patient averaged 83 ± 17%. The highest recurrence percentage was located in the RA in 5 patients and in the LA in 14 patients. Patients with sites of shortest mean cycle length of activations with the most recurrent morphology in the LA and RA had ablation failure rates of 25% and 100%, respectively (hazard ratio 4.95; P = .05).
A new technique to characterize electrogram morphology recurrence demonstrated that there is a distribution of sites with high and low repeatability of electrogram morphologies. Sites with rapid activation of highly repetitive morphology patterns may be critical to sustaining AF. Further testing of this approach to map and ablate AF sources is warranted.
Objective Surgical ablation of atrial fibrillation is generally safe and effective, but atrial fibrillation redevelops in approximately 20% of patients. We sought to determine anatomic factors, ...technology factors, or both that contribute to these failures. Methods Four hundred eight patients underwent 5 types of atrial fibrillation ablation depending on their atrial fibrillation history and need for concomitant surgical intervention: the classic maze procedure, high-intensity focused ultrasound, the left atrial maze procedure, the biatrial maze procedure, and pulmonary vein isolation. Ninety-five percent of patients with preoperative atrial fibrillation underwent surgical ablation. Results Patients undergoing high-intensity focused ultrasound had a high rate of late postoperative percutaneous ablation (37.5%) after surgical intervention ( P < .001 vs the other groups). At last follow-up, freedom from atrial fibrillation and need for ablation was as follows: classic maze procedure, 90%; high-intensity focused ultrasound, 43%; left atrial maze procedure, 79%; biatrial maze procedure, 79%; and pulmonary vein isolation, 69% ( P < .001 between groups). For those with atrial fibrillation, mapping and ablation were performed in 23.6% (n = 27), and all patients with high-intensity focused ultrasound had failure of the box lesion around the pulmonary veins. Of those with just the left atrial maze procedure or pulmonary vein isolation, the right atrium was the source for failure in 75% (6/8). Conclusions Patients undergoing high-intensity focused ultrasound had a high need for postoperative ablation and low freedom from atrial fibrillation. The classic maze procedure had the best results. Left atrial ablation might allow failure from right atrial foci. Matching the technology and lesion set to the patient yields good results and can be applied in 95% of patients. We suggest others obtain late catheter ablation to correct remaining atrial fibrillation, and add to the paucity of late data regarding failure mode.
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