|Year : 2008 | Volume
| Issue : 2 | Page : 52-55
|Date of Web Publication||17-Jun-2010|
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
. Cardiovascular News. Heart Views 2008;9:52-5
Cardiac Memory in Patients With Wolff-Parkinson-White Syndrome
Cardiac memory refers to a change in ventricular repolarization induced by and persisting for minutes to months after cessation of a period of altered ventricular activation (eg, resulting from pacing or preexcitation in patients with Wolff-Parkinson-White syndrome). ECG imaging (ECGI) is a novel imaging modality for noninvasive electroanatomic mapping of epicardial activation and repolarization.
Fourteen pediatric patients with Wolff-Parkinson-White syndrome and no other congenital disease, were imaged with ECGI a day before and 45 minutes, 1 week, and 1 month after successful catheter ablation. ECGI determined that preexcitation sites were consistent with sites of successful ablation in all cases to within a 1-hour arc of each atrioventricular annulus. In the preexcited rhythm, activation-recovery interval (ARI) was the longest (349 6 ms) in the area of preexcitation leading to high average base-to-apex ARI dispersion of 95 9 ms (normal is 40 ms). The ARI dispersion remained the same 45 minutes after ablation, although the activation sequence was restored to normal. ARI dispersion was still high (79 9 ms) 1 week later and returned to normal (45 6 ms) 1 month after ablation.
The study demonstrates that ECGI can noninvasively localize ventricular insertion sites of accessory pathways to guide ablation and evaluate its outcome in pediatric patients with Wolff-Parkinson-White syndrome. Wolff-Parkinson-White is associated with high ARI dispersion in the preexcited rhythm that persists after ablation and gradually returns to normal over a period of 1 month, demonstrating the presence of cardiac memory. The 1-month time course is consistent with transcriptional reprogramming and remodeling of ion channels.
Use of Cardiac Resynchronization Therapy in Patients Hospitalized with Heart Failure
The frequency and characterization of patients receiving cardiac resynchronization therapy (CRT) are largely unknown since the publication of pivotal clinical trials and subsequent incorporation of CRT into the American College of Cardiology/American Heart Association guidelines for heart failure.
Investigators analyzed 33 898 patients admitted from January 2005 through September 2007 to 228 hospitals participating in the American Heart Association's Get With the Guidelines-Heart Failure program. There were 4201 patients (12.4%) discharged alive with CRT, including 811 new implants. Patients discharged with CRT were older (median age, 75 versus 72 years) and had lower median left ventricular ejection fraction (30% versus 38%), more frequent ischemic cardiomyopathy (58% versus 45%), more history of atrial fibrillation (38% versus 27%), and higher rates of b-blocker and aldosterone antagonist use (P < 0.0001 for all) than those without CRT. The study found that 4.8% of patients with left ventricular ejection fraction ͳ 35% were discharged with a new CRT implant, which varied greatly by hospital. Ten percent of patients discharged with a new CRT implant had a left ventricular ejection fraction > 35%. Major factors associated with lower rates of new CRT placement were treatment in the northeast (odds ratio, 0.40; 95% confidence interval, 0.30 to 0.53), black race (odds ratio, 0.45; 95% confidence interval, 0.36 to 0.57), increasing left ventricular ejection fraction per 10% (odds ratio, 0.56; 95% confidence interval, 0.52 to 0.60), and increasing age per 10 years in those > 70 years of age (odds ratio, 0.56; 95% confidence interval, 0.48 to 0.65).
Although CRT is a recent evidence-based therapy for heart failure, patterns of use differ significantly from clinical trials and published guidelines. Important variations also exist for CRT therapy based on race, geographic region, comorbidities, and age and need to be addressed through further study and/or quality-of-care initiatives.
Physical Activity and Incidence of Atrial Fibrillation in Older Adults (The Cardiovascular Health Study)
Vigorous exertion and endurance training have been reported to increase atrial fibrillation (AF). Associations of habitual light or moderate activity with AF incidence have not been evaluated.
We prospectively investigated associations of leisure-time activity, exercise intensity, and walking habits, assessed at baseline and updated during follow-up visits, with incident AF, diagnosed by annual 12-lead ECGs and hospital discharge records, from 1989 to 2001 among 5446 adults 65 years of age in the Cardiovascular Health Study. During 47 280 person-years of follow-up, 1061 new AF cases occurred (incidence 22.4/1000 person-years). In multivariable-adjusted analyses, leisure-time activity was associated with lower AF incidence in a graded manner, with 25% (hazard ratio [HR] 0.75, 95% confidence interval [CI] 0.61 to 0.90), 22% (HR 0.78, 95% CI 0.65 to 0.95), and 36% (HR 0.64, 95% CI 0.52 to 0.79) lower risk in quintiles 3, 4, and 5 versus quintile 1 (P for trend < 0.001). Exercise intensity had a U-shaped relationship with AF (quadratic P = 0.02): Versus no exercise, AF incidence was lower with moderate-intensity exercise (HR 0.72, 95% CI 0.58 to 0.89) but not with high-intensity exercise (HR 0.87, 95% CI 0.64 to 1.19). Walking distance and pace were each associated with lower AF risk in a graded manner (P for trend < 0.001); when we assessed the combined effects of distance and pace, individuals in quartiles 2, 3, and 4 had 25% (HR 0.75, 95% CI 0.56 to 0.99), 32% (HR 0.68, 95% CI 0.50 to 0.92), and 44% (HR 0.56, 95% CI 0.38 to 0.82) lower AF incidence than individuals in quartile 1. Findings appeared unrelated to confounding by comorbidity or indication. After evaluation of cut points of moderate leisure-time activity (600 kcal/week), walking distance (12 blocks per week), and pace (2 mph), 26% of all new AF cases (95% CI 7% to 43%) appeared attributable to absence of these activities.
Light to moderate physical activities, particularly leisure-time activity and walking, are associated with significantly lower AF incidence in older adults.
Contemporary Analysis of Descending Thoracic and Thoracoabdominal Aneurysm Repair
Endovascular repair of thoracic aneurysm has demonstrated low risks of mortality and spinal cord ischemia (SCI), but few large series have been published on endovascular thoracoabdominal aneurysm repair, and reports suffer from a lack of accurate comparison with similar open surgical procedures.
A consecutive cohort of patients with thoracic and thoracoabdominal aneurysms treated electively with endovascular repair (ER) or surgical repair (SR) techniques between 2001 and 2006 were analyzed. The association between repair technique and SCI was evaluated with univariable analysis. Adjustments for potential confounders and for the propensity to receive ER or SR were also performed in multivariable analysis. A total of 724 patients (352 ER, 372 SR) underwent repair. The mean age was 67 years, and 65% were male. ER patients were on average 9 years older (P < 0.001), had more comorbid conditions, and more frequently had prior distal repair (P < 0.001) or underwent a type I or IV repair. SR patients more commonly had chronic dissection or required type II or type III repairs (P < 0.001). Mortality at 30 days (5.7% ER versus 8.3% SR, P = 0.2) and 12 months (15.6% ER versus 15.9% SR, P = 0.9) was similar. A borderline difference in SCI was found between repair techniques: 4.3% of ER and 7.5% of SR patients (P = 0.08) had SCI. In patients with ER, prior distal aortic operation was associated with the development of SCI in univariable analysis (odds ratio 4.1, 95% confidence interval 1.4 to 11.7). Multivariable analysis showed that the type of required repair (type I, II, III, or IV) was the primary factor associated with the development of SCI in ER and SR patients.
No significant difference in the incidence of mortality or SCI was found between ER and SR techniques. The strongest factor associated with SCI remains the extent of the disease. Further studies are indicated to compare ER with patients considered eligible for SR.
Routine Use of Bilateral Skeletonized Internal Thoracic Artery Grafting Long-Term Results
Skeletonized harvesting of the internal thoracic artery (ITA) decreases the severity of sternal devascularization, thus reducing the risk of postoperative sternal complications in patients undergoing bilateral ITA grafting.
Between 1996 and 2001, 1515 consecutive patients underwent skeletonized bilateral ITA grafting. Of the 1179 male and 336 female patients, 641 (42.3%) were > 70 years of age, and 519 (34.2%) had diabetes mellitus. Operative mortality was 2.8%. Early postoperative morbidity included sternal infection (1.6%), cerebrovascular accident (3%), and perioperative myocardial infarction (1%). Multiple regression analysis showed chronic obstructive pulmonary disease (odds ratio, 11.3; 95% confidence interval [CI], 4.45 to 28.55), repeat operation (odds ratio, 12.7; 95% CI, 3.25 to 49.56), and diabetes mellitus (non-insulin dependent: odds ratio, 4.64; 95% CI, 1.85 to 11.59; insulin dependent: odds ratio, 6.9; 95% CI, 1.35 to 35.27) to be associated with increased risk of sternal infection. Follow-up (between 5 and 12 years) revealed 305 late deaths. Kaplan-Meier 10-year survival rates for patients < 65, 65 to 74, and > 75 years of age were 87%, 75%, and 52%, respectively. Cox regression analysis revealed increased overall mortality (early and late) in patients with peripheral vascular disease (hazard ratio [HR], 1.8; 95% CI, 1.39 to 2.33), patients > 75 years of age (HR, 7.23; 95% CI, 4.16 to 12.55), those undergoing repeat operations (HR, 2.22; 95% CI, 1.27 to 3.89), patients with preoperative congestive heart failure (HR, 1.64; 95% CI, 1.29 to 3.75), and those with chronic renal failure (HR, 1.52; 95% CI, 1.11 to 2.01). Operations performed without cardiopulmonary bypass were associated with better postoperative survival (HR, 0.66; 95% CI, 0.49 to 0.87).
Bilateral ITA grafting is associated with low morbidity and good long-term results. Use of skeletonized bilateral ITA is appropriate for the elderly and most patients with diabetes; however, it is not recommended for repeat operations or for patients with chronic obstructive pulmonary disease.
Aliskiren is the first orally active inhibitor of renin to be approved for clinical use as an antihypertensive agent. The development program has established that at the licensed doses of 150 mg and 300 mg, there are dose-related falls in blood pressure comparable to those seen with other major classes of antihypertensive drugs and that these falls are associated with a placebo level of side effects. Aliskiren was found to be effective either as monotherapy or in combination with drugs from the other major classes. As expected, there was a greater benefit from adding aliskiren to natriuretic drugs than to other blockers of the renin system. However, there was also some consistent benefit from dual renin blockade. Aliskiren is likely to be of most value in patients uncontrolled by, or intolerant of, other classes. Rational understanding of the renin system will maximize its value, for instance, by encouraging greater use of natriuretic agents in patients with resistant hypertension to render their hypertension renin dependent. Whether there are cardiovascular benefits other than blood pressure control in blocking the renin system remains to be demonstrated. It is hoped that long-term outcome studies with aliskiren will finally allow this question to be answered.
Cardiac Troponin Elevation among Patients with Stable Coronary Artery Disease Undergoing Percutaneous Coronary Intervention
Although cardiac troponin (cTn) elevation is associated with periprocedural complications during percutaneous coronary intervention (PCI) in the setting of acute coronary syndromes, the prevalence and prognostic significance of preprocedural cTn elevation among patients with stable coronary artery disease undergoing PCI are unknown.
Between July 2004 and September 2006, 7592 consecutive patients who underwent attempted stent placement at 47 hospitals throughout the United States were enrolled in a prospective multicenter registry. The authors analyzed the frequency of an elevated cTn immediately before PCI and its relationship to in-hospital and 1-year outcomes among patients who underwent PCI for either stable angina or a positive stress test. Among the stable coronary artery disease population (n = 2382, 31.4%), 142 (6.0%) had a cTn level above the upper limit of normal before the procedure. Compared with patients who had normal baseline cTn, patients with elevated cTn had a higher rate of in-hospital death or myocardial infarction (13.4% versus 5.6%; P<0.001) and a trend toward higher rates of urgent repeat PCI (1.4% versus 0.2%; P = 0.06). In multivariable analyses adjusted for demographic, clinical, angiographic, and procedural factors, baseline cTn elevation remained independently associated with the composite of death or myocardial infarction at hospital discharge (odds ratio, 2.1; 95% confidence interval, 1.2 to 3.8; P = 0.01) and at the 1-year follow-up (odds ratio, 2.0; 95% confidence interval, 1.2 to 3.3; P = 0.005).
Baseline elevation of cTn is relatively common among patients with stable coronary artery disease undergoing PCI and is an independent prognostic indicator of ischemic complications. If these data are confirmed in future studies, consideration should be given to routine testing of cTn before performance of PCI in this patient population.
Does Sodium Nitroprusside Decrease the Incidence of Atrial Fibrillation after Myocardial Revascularization?
Atrial fibrillation (AF) often occurs after coronary artery bypass grafting and can result in increased morbidity and mortality. In the present pilot study, our aim was to investigate whether sodium nitroprusside (SNP), as a nitric oxide donor, can reduce the frequency of post-coronary artery bypass grafting AF.
To investigate the effectiveness of SNP in the prophylaxis of AF, we conducted a prospective, randomized, placebo-controlled clinical study on 100 consecutive patients in whom we performed elective and initial CABG operations. A control group of 50 patients were treated with placebo (dextrose 5% in water), whereas the SNP group (n = 50 patients) was treated with SNP (0.5 ΅g · kg-1 · min-1) during the rewarming period. High-sensitivity C-reactive protein levels were measured before surgery and 5 days postoperatively. All patients were monitored postoperatively with telemetry. Baseline characteristics were similar in both treatment groups. AF occurred in 12% of the SNP group and 27% of the control group. The occurrence of AF was significantly lower in the SNP group (P = 0.005). The duration of AF in the SNP group was significantly shorter than that in the control group (5.331.86 and 7.551.94 hours, respectively; P = 0.023). C-reactive protein levels were higher postoperatively in the control group than in the SNP group (P < 0.05). Postoperative AF significantly prolonged postoperative hospital stay (P < 0.05).
The incidence of postoperative AF in the SNP group was reduced significantly. Further studies are needed to better delineate the anti-AF profile of SNP.
Coronary Artery Bypass Surgery Versus Percutaneous Coronary Intervention in Patients with Multivessel Coronary Artery Disease: Six-Year Follow-Up From the Stent or Surgery Trial (SoS)
The Stent or Surgery Trial is a randomized, controlled trial comparing percutaneous coronary intervention with coronary artery bypass grafting (CABG) for patients with multivessel disease. Initial results at a median follow-up of 2 years showed a survival advantage for patients randomized to CABG. This article reports survival outcome at a median follow-up of 6 years.
A total of 988 (n = 488 percutaneous coronary intervention, n = 500 CABG) patients were randomized at 53 centers during the period from 1996 to 1999. Investigators established survival status from hospital or community medical records or national databases or by direct contact with patients and their relatives. All-cause mortality was compared with hazard ratios and confidence intervals calculated from Cox proportional hazards models. Prespecified subgroup analyses for diabetes mellitus, angina grade, and angiographic severity of coronary disease at baseline were performed with tests for interaction. At a median follow-up of 6 years, 53 patients (10.9%) died in the percutaneous coronary intervention group compared with 34 (6.8%) in the CABG group (hazard ratio 1.66, 95% confidence interval 1.08 to 2.55, P = 0.022). Little evidence was found that the treatment effect on mortality differed between subgroups according to baseline angina grade (interaction test P = 0.52), the severity of coronary disease (P = 0.92), or diabetic status (P = 0.15).
At a median follow-up of 6 years, a continuing survival advantage was observed for patients managed with CABG, which is not consistent with results from other stent-versus-CABG studies.
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