Composite Index Tagging for PVI in Paroxysmal AF: A Prospective, Multicenter Postapproval Study.

BACKGROUND: VISITAG SURPOINT (VS)-guided ablation of paroxysmal atrial fibrillation has demonstrated good short- and long-term success rates with low rates of complications in recent, predominantly European, studies. However, there is a lack of multicenter data from the United States. OBJECTIVES: This U.S. study evaluated the safety and effectiveness of VS ablation using a contact force-sensing catheter for the treatment of drug-refractory symptomatic paroxysmal atrial fibrillation. METHODS: The prospective, nonrandomized VS postapproval study was conducted at 32 U.S. sites. Ablation consisted of pulmonary vein isolation with recommended VS index targets (anterior, roof, or ridge: 550; posterior or inferior: 380). Additional non-pulmonary vein triggers were ablated at the investigators' discretion. Subjects were followed for 12 months, including a 3-month blanking period. The primary safety endpoint was the primary adverse event rate up to 7 days postablation. The primary effectiveness endpoint was 12-month freedom from atrial tachyarrhythmia recurrence and an additional set of failure modes based on stringent monitoring (weekly transtelephonic monitoring [TTM] [day 91 through month 5], monthly TTM [months 6 to 12], and any symptomatic cardiac episode using TTM, plus electrocardiogram [at discharge, 1 month, 3 months, 6 months, and 12 months] with 24-hour Holter monitoring [12 months]). RESULTS: Of 283 patients enrolled, 261 had the catheter inserted and underwent ablation (safety cohort); 246 met all eligibility criteria (effectiveness cohort). Mean fluoroscopy time was 2.2 minutes. Mean amount of catheter-delivered fluid was 671 mL; only 18.0% of patients utilized a Foley catheter. Primary safety and effectiveness endpoints were met. The raw primary adverse event rate was 4.3% (14 events, n = 11). At 12 months, the Kaplan-Meier estimate of freedom from primary effectiveness failure was 76.4%; estimates of 12-month freedom from documented atrial fibrillation, atrial tachycardia, or atrial flutter recurrence were 81.5% and 92.7% per stringent monitoring and standard-of-care monitoring (excluding TTM), respectively. The first-pass isolation rate was 83.1%, represented by no acute reconnection after the 30-minute waiting period. Freedom from repeat ablation at 12 months was 94.0%. CONCLUSIONS: The VS postapproval study confirms reproducibility of clinical safety and effectiveness of the standardized VS paroxysmal atrial fibrillation ablation workflow with >80% 12-month freedom from atrial tachyarrhythmia recurrence and first-pass isolation rate of 83.1%. Procedures were performed with minimal fluoroscopy. (Evaluation of VISITAG SURPOINT™ Module With External Processing Unit [EPU]; NCT03624881).

Positive Clinical Benefit on Patient Care, Quality of Life, and Symptoms After Contact Force-Guided Radiofrequency Ablation in Persistent Atrial Fibrillation: Analyses From the PRECEPT Prospective Multicenter Study.

BACKGROUND: There is limited evidence on the long-term clinical benefits of catheter ablation in patients with persistent atrial fibrillation. METHODS: PRECEPT was a prospective, multicenter, single-arm Food and Drug Administration-regulated investigational device exemption clinical study. Patients were followed up to 15 months after ablation. Outcomes included use of antiarrhythmic drugs, rate of cardioversions and cardiovascular hospitalization, Atrial Fibrillation Effect on Quality-of-Life score, and Canadian Cardiovascular Society Severity of Atrial Fibrillation score. RESULTS: A total of 333 enrolled persistent atrial fibrillation patients underwent ablation. The cardioversion rate decreased by 83% at the 9- to 15-month follow-up. Antiarrhythmic drug utilization decreased by 69% at 12 to 15 months post-ablation. The Kaplan-Meier estimate of freedom from cardiovascular hospitalization was 84.2% (95% CI, 80.2%-88.2%) at 15 months. Consistent improvements in mean Atrial Fibrillation Effect on Quality-of-Life composite (+50.0) were seen at 6 months, sustained at 15 months, and exceeded the minimum clinically important difference. Improvements in Atrial Fibrillation Effect on Quality-of-Life scores were significantly better among participants without documented atrial arrhythmia recurrences. By Canadian Cardiovascular Society Severity of Atrial Fibrillation symptom classification, >80% of patients were asymptomatic (class 0) at 15 months post-ablation compared with only 0.7% at baseline. CONCLUSIONS: Contact force-guided radiofrequency ablation of persistent atrial fibrillation was associated with a significant decrease in antiarrhythmic drug use, cardioversion rate, and hospitalization. Clinically meaningful improvements in quality of life were observed in all patients. The majority of the patients (>80%) were asymptomatic at 15 months post-ablation. The positive clinical impact of improved quality of life and reduced health care utilization may help with shared decision-making in persistent atrial fibrillation treatment. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02817776.

Changes in quality of life, cognition and functional status following catheter ablation of atrial fibrillation.

OBJECTIVE: To investigate changes in quality of life (QoL), cognition and functional status according to arrhythmia recurrence after atrial fibrillation (AF) ablation. METHODS: We compared QoL, cognition and functional status in patients with recurrent atrial tachycardia (AT)/AF versus those without recurrent AT/AF in the AXAFA-AFNET 5 clinical trial. We also sought to identify factors associated with improvement in QoL and functional status following AF ablation by overall change scores with and without analysis of covariance (ANCOVA). RESULTS: Among 518 patients who underwent AF ablation, 154 (29.7%) experienced recurrent AT/AF at 3 months. Patients with recurrent AT/AF had higher mean CHA2DS2-VASc scores (2.8 vs 2.3, p<0.001) and more persistent forms of AF (51 vs 39%, p=0.012). Median changes in the SF-12 physical (3 (25th, 75th: -1, 8) vs 1 (-5, 8), p=0.026) and mental scores (2 (-3, 9) vs 0 (-4, 5), p=0.004), EQ-5D (0 (0,2) vs 0 (-0.1, 0.1), p=0.027) and Karnofsky functional status scores (10 (0, 10) vs 0 (0, 10), p=0.001) were more favourable in patients without recurrent AT/AF. In the overall cohort, the proportion with at least mild cognitive impairment (Montreal Cognitive Assessment <26) declined from 30.3% (n=157) at baseline to 21.8% (n=113) at follow-up. ANCOVA identified greater improvement in Karnofsky functional status (p<0.001) but not SF-12 physical (p=0.238) or mental scores (p=0.065) in those without recurrent AT/AF compared with patients with recurrent AT/AF. CONCLUSIONS: Patients without recurrent AT/AF appear to experience greater improvement in functional status but similar QoL as those with recurrent AT/AF after AF ablation.

Persistent Atrial Fibrillation Ablation With Contact Force-Sensing Catheter: The Prospective Multicenter PRECEPT Trial.

OBJECTIVES: This study sought to evaluate the safety and effectiveness of catheter ablation of persistent atrial fibrillation (PsAF) using a porous tip contact force-sensing catheter. BACKGROUND: Although the safety and effectiveness of catheter ablation of paroxysmal atrial fibrillation are established, there are limited data on outcomes in patients with PsAF. As such, no ablation catheter is currently approved by the Food and Drug Administration for PsAF ablation. METHODS: The prospective, multicenter, nonrandomized PRECEPT (Prospective Review of the Safety and Effectiveness of the THERMOCOOL SMARTTOUCH SF Catheter Evaluated for Treating Symptomatic PersistenT AF) study was conducted at 27 sites in the United States and Canada. Enrollment criteria included documented symptomatic PsAF and nonresponse or intolerance to ≥1 antiarrhythmic drug (Class I or III). An individualized treatment approach was used including pulmonary vein isolation with ablation of additional targets permitted at the investigators' discretion. To optimize treatment outcomes, a 3-month post-ablation medication adjustment period followed by a 3-month therapy consolidation period were included. Arrhythmia recurrences were stringently monitored by monthly and symptomatic transtelephonic monitoring, electrocardiography, and Holter monitoring for up to 15 months after ablation. RESULTS: Of 381 enrolled participants, 348 had the investigational catheter inserted and underwent ablation. The primary adverse event rate was 4.1% (15 events in 14 participants). Kaplan-Meier analyses estimated a primary effectiveness success rate of 61.7% and a clinical success rate of 80.4% at 15 months. CONCLUSIONS: The results demonstrate the clinical safety and effectiveness of PsAF ablation using contact force-sensing technologies. The primary adverse event was within the expected range and similar to those reported in historical studies of paroxysmal AF ablation. (Prospective Review of the Safety and Effectiveness of the THERMOCOOL SMARTTOUCH SF Catheter Evaluated for Treating Symptomatic PersistenT AF; NCT02817776).

Apixaban in patients at risk of stroke undergoing atrial fibrillation ablation.

Aims: It is recommended to perform atrial fibrillation ablation with continuous anticoagulation. Continuous apixaban has not been tested. Methods and results: We compared continuous apixaban (5 mg b.i.d.) to vitamin K antagonists (VKA, international normalized ratio 2-3) in atrial fibrillation patients at risk of stroke a prospective, open, multi-centre study with blinded outcome assessment. Primary outcome was a composite of death, stroke, or bleeding (Bleeding Academic Research Consortium 2-5). A high-resolution brain magnetic resonance imaging (MRI) sub-study quantified acute brain lesions. Cognitive function was assessed by Montreal Cognitive Assessment (MoCA) at baseline and at end of follow-up. Overall, 674 patients (median age 64 years, 33% female, 42% non-paroxysmal atrial fibrillation, 49 sites) were randomized; 633 received study drug and underwent ablation; 335 undertook MRI (25 sites, 323 analysable scans). The primary outcome was observed in 22/318 patients randomized to apixaban, and in 23/315 randomized to VKA {difference -0.38% [90% confidence interval (CI) -4.0%, 3.3%], non-inferiority P = 0.0002 at the pre-specified absolute margin of 0.075}, including 2 (0.3%) deaths, 2 (0.3%) strokes, and 24 (3.8%) ISTH major bleeds. Acute small brain lesions were found in a similar number of patients in each arm [apixaban 44/162 (27.2%); VKA 40/161 (24.8%); P = 0.64]. Cognitive function increased at the end of follow-up (median 1 MoCA unit; P = 0.005) without differences between study groups. Conclusions: Continuous apixaban is safe and effective in patients undergoing atrial fibrillation ablation at risk of stroke with respect to bleeding, stroke, and cognitive function. Further research is needed to reduce ablation-related acute brain lesions.

Thermogenic supplement use does not alter characteristics of sudden death in the young.

BACKGROUND: To evaluate supplement use, most notably ephedra, which has been temporally associated with sudden death. Animal models suggest increased myocardial irritability may predispose to primary arrhythmic death. METHODS: Clinical, pathological, and investigative records from the Office of the Armed Forces Medical Examiner's Cardiovascular Death Registry were reviewed. Forty-eight cases of those with known supplement use were compared to 144 age-, gender-, and socioeconomic-matched controls in a 1:3 case:control manner. RESULTS: Of the 48 sudden deaths temporally associated with supplement use, the mean age was 34.2 ± 10.0 years and predominantly male (n = 44, 91.7%). The underlying cause of death was fatal atherosclerotic coronary disease in 18 (37.5%), sudden unexplained death in 16 (33.3%), and hypertrophic cardiomyopathy in six (12.5%). Compared with controls, there were no statistically significant differences in adjudicated cause of death. On autopsy, there were no differences in cardiac mass, ventricular wall thickness, or presence of atherosclerosis in those known to be taking identified supplements compared to a control population. In the subject ≥35 years, and known to be taking supplements, there was a significant increase in causality of death as due to sudden unexplained death (relative risk = 5.1 [95% confidence interval, 1.4-18.7]). CONCLUSIONS: Active surveillance of mortality in an autopsy-derived series of young adults finds atherosclerotic coronary disease and idiopathic sudden death are common etiologies of death when taking supplements, but no cardiac structural or histologic mechanism to suggest different pathologic process than a matched control population.

Management of central venous gradient using excimer laser lead extraction of chronic indwelling pacemaker leads in the setting of ipsilateral arteriovenous fistula.

Device therapy is becoming common in those patients with renal insufficiency. Coexisting need for arteriovenous (AV) fistula placement is often contemplated relative to device placement. We describe the excimer laser lead extraction of a malfunctioning chronic atrial pacemaker lead ipsilateral to an AV fistula.

Sudden death in young adults: an autopsy-based series of a population undergoing active surveillance.

OBJECTIVES: The purpose of this study was to define the incidence and characterization of cardiovascular cause of sudden death in the young. BACKGROUND: The epidemiology of sudden cardiac death (SCD) in young adults is based on small studies and uncontrolled observations. Identifying causes of sudden death in this population is important for guiding approaches to prevention. METHODS: We performed a retrospective cohort study using demographic and autopsy data from the Department of Defense Cardiovascular Death Registry over a 10-year period comprising 15.2 million person-years of active surveillance. RESULTS: We reviewed all nontraumatic sudden deaths in persons 18 years of age and over. We identified 902 subjects in whom the adjudicated cause of death was of potential cardiac etiology, with a mean age of 38 ± 11 years. The mortality rate for SCD per 100,000 person-years for the study period was 6.7 for males and 1.4 for females (p < 0.0001). Sudden death was attributed to a cardiac condition in 715 (79.3%) and was unexplained in 187 (20.7%). The incidence of sudden unexplained death (SUD) was 1.2 per 100,000 person-years for persons <35 years of age, and 2.0 per 100,000 person-years for those ≥ 35 years of age (p < 0.001). The incidence of fatal atherosclerotic coronary artery disease was 0.7 per 100,000 person-years for those <35 years of age, and 13.7 per 100,000 person-years for those ≥ 35 years of age (p < 0.001). CONCLUSIONS: Prevention of sudden death in the young adult should focus on evaluation for causes known to be associated with SUD (e.g., primary arrhythmia) among persons <35 years of age, with an emphasis on atherosclerotic coronary disease in those ≥ 35 years of age.

High-velocity penetrating thoracic trauma with suspected cardiac involvement in a combat support hospital.

PURPOSE: The most common cardiac injuries in the United States are blunt trauma from motor vehicle accidents or low-velocity trauma from stabbings. During military conflict, high-velocity injuries, including gunshot wounds (GSW) and fragment injury from improvised explosive devices (IED), are relatively more common. METHODS: This is a retrospective review of cases with high-velocity penetrating injury and suspected myocardial involvement during a 6-month period in Baghdad, Iraq, at a United States Army hospital during Operation Iraqi Freedom. RESULTS: Eleven cases survived to admission (GSW in 5, IED in 6). The mean age of the all-male cohort was 27 years (range, 3-54 years). Eight of the 11 patients (73%) were victims of polytrauma. The entrance involved the right ventricle (n = 3), right atrium (n = 2), left ventricle (n = 1), or mediastinum and pericardial reflections (n = 5). Echocardiography was performed in all 11 patients. In 7 patients, no foreign body was identifiable, and in 2 patients the foreign body was identified within the pericardial fat pad. Three patients were identified as having a suspected ventricular septal defect, ranging in size from 2 to 8 mm. The most common electrocardiographic abnormality was atrioventricular block and right bundle branch block. In 4 patients, the management of the chest injury was nonsurgical, and in 1 patient the treatment was a chest tube only. Four of the patients underwent median sternotomy, 1 underwent emergent lateral thoracotomy, and 1 underwent an infradiaphragmatic approach. CONCLUSION: This case series is too small to draw definitive conclusions; however, a multidisciplinary approach to high-velocity injuries with potential for cardiac involvement augments preoperative assessment for myocardial injury and may allow selective nonoperative management.

Resource utilization in the management of young patients with syncope in a combat theater of operations.

UNLABELLED: Clinical features of young patients presenting with syncope have been underreported. METHODS: Retrospective review using U.S. Military Health System's Theater Medical Data Store and Joint Medical Workstation identified patients evaluated for syncope from January 2005 to October 2007 while deployed to a combat zone. RESULTS: We identified 848 patients with syncope. The majority (80.8%) were under the age of 40. The diagnostic yield of the ECG was 2.0%. In those <40 years, there were no head CTs or transthoracic echocardiograms that identified a cause of syncope. There was no difference in evacuation out of theater between those <40 years and those >40 years (10.8% vs. 8.6%, p = 0.08). Patients with a prior episode of syncope were more likely to undergo medical evacuation outside of the combat zone (16.0% vs. 7.7%, p < 0.01). DISCUSSION: Evacuation of those <40 years to facilities with advanced imaging did not add diagnostic information.

Differential manifestation of cardiovascular complaints as a function of utilization of ergogenic supplements.

INTRODUCTION: The rate of use of dietary supplements among young adults is significant. While the military makes significant restrictions on the use of certain pharmacologic drugs and actively tests for illegal drugs in a deployed environment, there is a near-unlimited supply of body-enhancing supplements available at military exchanges to deployed personnel. By emphasizing physical performance and providing these for purchase, the military leadership, perhaps unknowingly, endorses the use of these products. Cardiovascular symptoms represent one of the leading nontraumatic causes of aeromedical evacuation from a combat zone. Whether the use of supplements is associated with a differential presentation to cardiovascular complaint is unknown. METHODS: Retrospective review using the US Department of Defense Military Health System data, we identified patients evaluated for cardiovascular complaints of syncope or palpitations while deployed to Iraq and Afghanistan. RESULTS: There were 905 US military personnel who presented with complaint of syncope or palpitations (mean age 31 +/- 10 years, 77% male). There were 83 (9.2%) who self-reported taking an ergogenic supplement. The incidence of reported use of supplements among males was 10.8%, which was significantly higher than its use among females at 3.8% (P = 0.001). In those >30 years, those on supplements had a higher resting pulse (90 +/- 28 vs 79 +/- 24 beats/min, P = 0.032), and the incidence of resting tachycardia was three-fold higher (35.0% vs 11.4%, P = 0.008). Supplement use was seen in 12.3% of those who presented with palpitations, which was significantly higher than those who presented without palpitations (7.8%, P = 0.043). In those taking supplements, symptoms were more likely during exertion (26.5% vs 15.0%, P < 0.001), and immediately postexertional (13.2% vs 4.6%, P < 0.001). An electrocardiogram was suggestive of diagnosis in 103 (16.3%), while head computed tomography, treadmill, and echocardiogram had no diagnostic utility in this patient population. DISCUSSION: In a healthy population serving within a combat zone, there exists a differential expression of disease in those taking supplements. Further study of a prospective nature to determine the impact of supplement use in this environment may allow for a more refined policy toward use and medical evaluation.

Gender differences and risk of ventricular tachycardia or ventricular fibrillation.

BACKGROUND: Healthy women have longer QT intervals and more drug-induced proarrhythmia compared to men, yet those given implantable cardioverter-difibrillators (ICDs) for ischemic cardiomyopathy have fewer episodes of ventricular tachycardia/ventricular fibrillation (VT/VF) than men. The role of repolarization duration and stability in arrhythmogenesis in men and women with structural heart disease has not been explored. OBJECTIVES: The purpose of this study was to analyze repolarization differences between men and women and their relation to the risk of VT/VF. METHODS: Multicenter Automatic Defibrillator Trial II study patients underwent 10-minute, resting digitized recordings at study entry. QT and heart rate were measured for each beat with a semiautomated method. QT variance was normalized for mean QT (QTVN) or for heart rate variance (QTVI). Spectral analysis of heart rate and QT time series was performed; coherence was indexed to quantify consistency of heart rate and QT power spectra. The incidence of VT/VF was determined by ICD interrogation. RESULTS: There were 805 usable recordings (142 females); 463 received ICDs (86 females). There was no gender difference in mean or median QT, QTc, or heart rate. QTVN and QTVI were slightly (but significantly) higher, and the mean coherence was lower in women. In a Cox multivariate analysis, increased QTVN or QTVI (top quartile) was associated with a significantly higher risk for VT/VF in men (QTVN hazard ratio (HR) 2.2; confidence interval [CI] 1.4-3.4; P = .001; QTVI HR 1.9; CI 1.2-3.0; P = .006) but not in women, while reduced coherence (bottom quartile) predicted VT/VF in women (HR 3.3; CI 1.2-9.0; P = .021) but not in men. CONCLUSIONS: In post-myocardial infarcation patients with depressed ejection fraction, both women and men manifest increased temporal variability in the QT interval. In men, QT variability by itself raised arrhythmic risk. In women, however, QT variability dissociated from HR variability (low coherence) appeared to be a uniquely significant predictor of arrhythmic events.

Cardiovascular disease in a forward military hospital during operation iraqi freedom: a report from deployed cardiologists.

BACKGROUND: No published data are available regarding cardiac evaluations in a forward military hospital setting. METHODS: Two cardiologists deployed in support of Operation Iraqi Freedom identified all of their cardiac evaluations. Patient demographic data, evaluations performed, outcomes, and return-to-duty rates were determined. RESULTS: Four hundred sixty-nine predominantly male patients were evaluated, with a mean age of 39 +/- 10 years. The most common reasons for referral were ischemic evaluation (n=283), arrhythmia/palpitations (n=83), and syncope (n=57). Of those referred with ischemia, the mean Framingham 10-year event risk calculated was low at 5.3 +/- 3.1%; 86% of military patient evaluations revealed no identifiable cardiovascular pathological condition, and patients were returned to duty. CONCLUSIONS: Cardiology support, with the availability of echocardiography and stress testing in the theater of operations, was able to provide cardiovascular consultative evaluations and management and to reduce rates of medical evacuations out of the theater of operations.

Reversal of left ventricular dysfunction following ablation of atrial fibrillation.

BACKGROUND: Evaluation of ventricular rate control in atrial fibrillation (AF) can be difficult, and the presence of an AF-induced ventricular cardiomyopathy due to intermittent poor rate control or other causes may be underestimated. The outcome with AF ablation in patients with a decreased left ventricular ejection fraction (LVEF) may provide insight into this important clinical issue. OBJECTIVE: To determine the effect of pulmonary vein isolation on LVEF in patients with AF and decreased LVEF (< or = 50%). METHODS: Ablation consisted of proximal isolation of arrhythmogenic pulmonary veins (PVs) and elimination of non-PV triggers. LVEF was determined within 24 hours after ablation and again at up to 6 months follow-up. Transtelephonic monitoring was performed routinely for 2-3 weeks prior to ablation, at 6 weeks, and 6 months post and with symptoms following ablation. AF control was defined as freedom from AF or marked (>90%) reduction in AF burden on or off previously ineffective antiarrhythmic medication. RESULTS: AF ablation was performed in 366 patients and 67 (18%) patients had decreased LV function with a mean LVEF of 42 +/- 9%. An average of 3.4 +/- 0.9 PVs were isolated. AF control in the depressed LVEF group compared favorably with the normal EF group (86% vs. 87% P = NS), although more redo procedures were required (1.6 +/- 0.8 vs 1.3 +/- 0.6 procedures; P < or = 0.05). Only 15 of 67 patients (22%) with decreased LVEF had shown tachycardia (>100 bpm) on repeated preablation ECG recordings during AF. In the decreased LVEF group, the LVEF increased from 42 +/- 9% to 56 +/- 8% (P < 0.001) after ablation. CONCLUSIONS: Patients with AF and decreased LVEF undergoing AF ablation have similar success to patients with normal LVEF and have improvement in LVEF after ablation. These results suggest the presence of a reversible AF-induced ventricular cardiomyopathy in many patients with AF and depressed LV function. The presence of under-recognized and reversible cardiomyopathy even when tachycardia is not persistent is important to recognize.

A prospective evaluation of the effect of simvastatin on heart rate variability in non-ischemic cardiomyopathy.

BACKGROUND: Modulation of sympathetic tone may contribute to statin-mediated reduction in sudden cardiac death. We examined the effect of simvastatin on heart rate variability (HRV) in patients with non-ischemic dilated cardiomyopathy to evaluate for an antisympathetic effect of statins independent of anti-ischemic properties. METHODS: The study was a prospective, open-label, self-controlled trial. Frequency domain analysis of HRV was assessed in 25 patients with non-ischemic dilated cardiomyopathy at baseline and after a 6-week course of simvastatin. The primary end point was the change in 5-minute sitting total spectral power (TSP) as a composite measurement of autonomic nervous system modulation. Secondary end points included the change in respiratory frequency area (RFa) with deep breathing (parasympathetic stress) and in low-frequency area (LFa) with Valsalva (sympathetic stress). RESULTS: Simvastatin had no effect on 5-minute sitting TSP (baseline 1932 +/- 1165 vs posttreatment 2570 +/- 1877 square milliseconds, P = .770), RFa with deep breathing (baseline 19 +/- 7 vs posttreatment 14 +/- 4 [beat/min]2, P = .31), or LFa with Valsalva (baseline 26 +/- 6 vs posttreatment 32 +/- 8 [beat/min]2, P = .342). Bivariate analysis demonstrated no correlation between low-density lipoprotein (LDL) change and change in TSP or RFa, but did demonstrate an inverse relationship between change in LDL and change in LFa with Valsalva stress (r = -0.45 and P = .041). CONCLUSION: Although simvastatin did not change baseline HRV, a modest relationship exists between the extent of LDL reduction and sympathetic responsiveness to stress.

QT interval variability and spontaneous ventricular tachycardia or fibrillation in the Multicenter Automatic Defibrillator Implantation Trial (MADIT) II patients.

OBJECTIVES: This study aimed to determine whether increased QT interval variability is associated with an increased risk for ventricular tachycardia (VT) or ventricular fibrillation (VF), documented by interrogation of the implantable cardioverter-defibrillator (ICD), in patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial (MADIT) II. BACKGROUND: Unstable repolarization has been proposed as a risk factor for re-entrant arrhythmias, but confirmatory data from clinical trials are lacking. METHODS: The QT variability was assessed in 10-min, resting high-resolution electrocardiogram recordings at study entry using a semiautomated algorithm that measured beat-to-beat QT duration in 817 MADIT II patients. The incidence of VT/VF requiring device therapy was determined by ICD interrogation. RESULTS: Median normalized QT variability (QTVN) was 0.179 and 0.125, respectively, in patients with VT/VF versus those without VT/VF (p = 0.001); QTVI (QTVN adjusted for heart rate variance) also was significantly (p < 0.05) higher in VT/VF patients than in those without VT/VF. Either QTVN or QTVI was linked with a significantly higher probability of VT/VF: two-year risk of VT/VF from Kaplan-Meier curves was 40% in highest quartile versus 21% in lower quartiles for QTVN, and 37% versus 22% for QTVI (p < 0.05 for each). In multivariate Cox regression models adjusting for clinical covariates (race, New York Heart Association functional class, time after myocardial infarction), top-quartile QTVI and QTVN were independently associated with VT/VF (hazard ratio for QTVN 2.18, 95%confidence interval [CI] 1.34 to 3.55, p = 0.002; hazard ratio for QTVI 1.80, 95% CI 1.09 to 2.95, p = 0.021). CONCLUSIONS: In postinfarction patients with severe left ventricular dysfunction, increased QT variability, a marker of repolarization lability, is associated with an increased risk for VT/VF.

Chronotropic incompetence in a young adult: case report and literature review.

Chronotropic incompetence (CI) is the inability of heart rate response to meet metabolic demand. CI is associated with sinus node dysfunction, atrial fibrillation, or structural heart disease, and can lead to functional impairment. We report the case of a 34-year-old man with CI secondary to sinus node dysfunction who demonstrated significant improvement in functional capacity with rate-responsive pacing. Therapy for CI should be guided by the treatment of the underlying cause with consideration for rate-responsive pacing in symptomatic patients. The prognosis of CI is variable and dependent on underlying etiology.