Jane Kruse

Gender-specific differences in the QT interval and the effect of autonomic tone and menstrual cycle in healthy adults.

Gender differences in the corrected QT interval have been noted since Bazetts initial description during the 1920s. The mechanism of this gender difference is unknown, and this study was undertaken to evaluate potential autonomic and menstrual cycle effects on the QT interval. The study population consisted of a healthy volunteer sample of 23 women and 20 men. Twelve-lead electrocardiographic determinations were made at rest and following double autonomic blockade (with atropine and propranolol) during the menstrual, follicular, and luteal phases of the menstrual cycle. Men were studied during 3 separate visits as controls. The corrected QT interval at baseline tended to be longer in women than men (421 +/- 16 ms vs 414 +/- 15 ms: p <0.07). Following double autonomic blockade, the corrected QT interval increased to 439 +/- 11 ms: p <0.001). However, the gender difference in corrected QT interval was unchanged (443 +/- 15 ms vs 437 +/- 12 ms). At baseline, there was no significant difference in the corrected QT interval among the 3 phases of the menstrual cycle (421 +/- 10, 423 +/- 18, and 420 +/- 18 in the menstrual, follicular, and luteal phases, respectively) and the corrected QT interval was longer in women than men at each visit. Following double autonomic blockade, the corrected QT interval in women was shorter in the luteal phase (438 +/- 16 ms) versus the menstrual (446 +/- 15 ms) or the follicular phase (444 +/- 13 ms; p <0.05). However, this difference, which was not present at baseline, does not appear to be responsible for the gender difference in the QT interval at rest. In conclusion, our results confirm that the corrected QT interval tends to be longer in women than men. Differences in autonomic tone and menstrual cycle variability in the corrected QT in women at rest do not appear to be responsible for the gender differences in the QT interval. The mechanism responsible for the longer QT interval in women remains to be defined.

Gender differences in heart rate before and after autonomic blockade: Evidence against an intrinsic gender effect

OBJECTIVES To document gender differences in heart rate in healthy young adult men and women, and examine the degree to which autonomic tone and other variables may be associated with the gender differences in heart rate. DESIGNS Cohort study. SETTINGS Clinical Research Center of a tertiary care medical center. PATIENTS A volunteer sample of 20 healthy men and 23 healthy women between ages 21 and 39 years. INTERVENTIONS Subjects were each studied three times: during the menstrual, follicular, and luteal phases of the menstrual cycle in women; and 5 to 10 days apart in men. Electrocardiograms (ECGs) were obtained at baseline and following double autonomic blockade with propranolol 0.2 mg/kg and atropine 0.04 mg/kg. Maximum exercise capacity was determined by bicycle ergometry. MAIN OUTCOME MEASURES Sinus cycle length at baseline and following double autonomic blockade, before and after correction for confounding variables. RESULTS Men had longer sinus cycle length both at baseline and after double autonomic blockade (971 +/- 88 ms versus 918 +/- 115 ms, P < 0.02, and 645 +/- 41 ms versus 594 +/- 57 ms, P < 0.0001). Sinus cycle length in women was longer than during the menstrual than luteal phase but this difference could not account for the gender difference in sinus cycle length. Men also had a greater maximum exercise capacity than women (1295 +/- 167 kpm/min versus 857 +/- 227 kpm/min; P < 0.0001). By analysis of covariance, maximum exercise capacity was the most significant predictor of sinus cycle length (P < 0.0003 at baseline, and P < 0.001 post blockade) and gender did not have a significant effect. The relationship of maximum exercise capacity to sinus cycle length was blunted but not abolished by autonomic blockade. CONCLUSIONS Sinus cycle length is longer in men than women. This difference appears to be associated with a gender difference in exercise capacity rather than intrinsic gender related properties of the sinus node or differences in autonomic tone. In addition, exercise induced bradycardia is mediated by both autonomic and nonautonomic factors in both genders.

Where does atrial fibrillation surgery fail? Implications for increasing effectiveness of ablation

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.

Midterm survival in patients treated for atrial fibrillation: A propensity-matched comparison to patients without a history of atrial fibrillation

OBJECTIVE Patients undergoing cardiac surgery with a history of untreated atrial fibrillation have reduced survival compared with similar patients without atrial fibrillation. We sought to compare the midterm survival of patients who received concomitant surgical ablation treatment for atrial fibrillation (atrial fibrillation ablated) with that of matched patients without a history of atrial fibrillation (no atrial fibrillation). METHODS We evaluated 3262 consecutive patients (813 [25%] with atrial fibrillation and 2449 [75%] without preoperative atrial fibrillation) undergoing cardiac surgery at a single institution from April 2004 to April 2009. Of patients with atrial fibrillation, 565 (70%) were treated with a concomitant surgical ablation procedure. Propensity scores were calculated on the basis of 37 known preoperative risk factors and yielded 744 patients. Midterm survival was compared between patients with atrial fibrillation ablation (n = 372) and patients without atrial fibrillation (n = 372). Survival was also compared between patients with successful vs unsuccessful ablation, and a matched analysis was performed at 1 year between the 2 groups. RESULTS Mean follow-up was 2.7 ± 1.6 years. Patients without atrial fibrillation and patients with treated atrial fibrillation had similar early 30-day mortality (1.2% vs 0.3%, P = .37) and overall mortality rates (11.6% vs 9.4%, P = .344), respectively. Survival analysis showed no differences at 1, 3, and 5 years between the 2 groups (log-rank P = .22). At last follow-up, 78% of treated patients were free of atrial fibrillation. At 1 year, 68% of patients were free of atrial fibrillation and antiarrhythmic medication. Freedom from atrial fibrillation and antiarrhythmic medication at 1 year predicted improved midterm survival (P = .03) compared with patients in atrial fibrillation or taking antiarrhythmic medication. Propensity-matched analysis after 1 year demonstrated improved survival for patients who were successfully treated (P = .016). CONCLUSIONS Patients undergoing surgical treatment of atrial fibrillation had survival similar to that of patients without a history of atrial fibrillation. Those with successful sinus restoration had improved survival compared with those who were treated but remained in atrial fibrillation.

Improvements in Health-Related Quality of Life Before and After Isolated Cardiac Operations

BACKGROUND Our study compared health-related quality of life (HRQOL) among cardiac surgical patient groups before and after cardiac operations for isolated surgical procedures and examined cardiac surgical patient HRQOL within the context of United States population norms. METHODS Of 2524 patients undergoing cardiac operations, 370 underwent isolated procedures (coronary artery bypass grafting, 136; aortic valve repair or replacement, 96; mitral valve repair or replacement, 92; Maze procedures, 46) between April 18, 2004, and June 30, 2008. They completed Short Form 36 questionnaires at baseline, at 3, 6, and 12 months postoperatively, and annually thereafter. Statistical analyses included χ(2), analysis of variance, longitudinal modeling, and longitudinal multivariable analyses. RESULTS Overall, the 370 cardiac surgical patients were 61.5 ± 11.9 years old, 70% men, and 76% white. Significant baseline differences in HRQOL existed among the cardiac surgical groups. Physical and mental components of the Short Form 36 improved from baseline to within 3 to 6 months postoperatively and remained stable through 3 years for all groups. When demographic and clinical covariates were held constant, the effect of cardiac surgical type on postsurgical HRQOL changes was not significant. CONCLUSIONS HRQOL improves early after cardiac operations and remains relatively constant long-term, independently of procedure type.

Surgery for atrial fibrillation

The field of atrial fibrillation is evolving rapidly. Although a medical rhythm control strategy has not proven to be beneficial for survival, new interventional therapies have improved the rate of sinus restoration and thus have the potential to improve outcomes. In particular, the maze procedure can be performed safely and cures the majority of patients with atrial fibrillation. Over the last two decades, the introduction of new ablation technologies has made the procedure much easier to perform and it is now more widely applied to patients with atrial fibrillation undergoing cardiac surgery. Minimally invasive modifications of the maze using these technologies have offered an important step towards developing a stand-alone procedure for the cure of atrial fibrillation with potentially decreased morbidity. We review the magnitude of the problem, the history of past surgical treatments, current surgical options and the future direction of surgical therapy.

Late neurologic events after surgery for atrial fibrillation: rare but relevant.

BACKGROUND The classic cut and sew maze is thought to reduce stroke, in part because of left atrial appendage (LAA) elimination. Multiple LAA elimination techniques have evolved with the introduction of new surgical treatment options for atrial fibrillation (AF), but the impact on stroke remains unknown. We studied the rate of late neurologic event (LNE) in the era of contemporary AF surgery. METHODS From April 21, 2004, to June 30, 2011, 773 patients underwent surgery for AF. In 131 patients, the LAA was excised. In 579, alternative elimination techniques were used (97 external ligation, 313 internal ligation, 126 stapled excision, 23 stapled excision plus internal ligation, 5 internal plus external ligations, and 15 that did not fit into any category); 63 LAAs were left intact and excluded from analyses. Complete follow-up was obtained by medical record review and phone call. Median survival follow-up was 3.3 years (first and third quartiles, 1.6 and 5.0). An LNE was defined as either a documented stroke or transient ischemic attack 30 or more days after surgery. Baseline characteristics and outcomes between LAA techniques were compared using χ(2), Fishers exact tests, and Students t tests. RESULTS There were 25 LNEs (3.5%) overall; the median occurrence time was 3.6 years (first and third quartiles, 1.9 and 5.4) after surgery. There were 17 strokes and 8 transient ischemic attacks. Of 45 demographic and surgical variables, only age, aortic valve surgery, and perioperative neurologic event (<30 days after cardiac surgery) independently predicted LNE (p = 0.003, 0.021, and 0.010, respectively). Late neurologic events occurred with an annual rate of 1.13% in patients with alternative elimination techniques, and 0.20% in patients with excised LAA (p = 0.001). Patients in AF at any time were more likely to have LNE, but this was not an independent predictor. CONCLUSIONS After surgery for AF ablation, there is ongoing low risk of LNE even when the LAA is surgically excised. Further investigation should be pursued to clarify whether a difference exists with alternative elimination techniques and in patients in whom AF is successfully eliminated.

Effect of informed consent on anxiety in patients undergoing diagnostic electrophysiology studies

The process of informed consent has been suspected to raise patient anxiety, but this supposition has not been well studied or validated. The aim of this study was to evaluate the effect of a detailed informed consent protocol on patient anxiety. Fifty patients (36 men, 14 women, mean age 55 +/- 18 years) undergoing diagnostic cardiac electrophysiologic studies were enrolled. Patients were randomly assigned to receive either a consent that did not detail specific risks regarding the procedure (consent A) or one that detailed the risks (consent B). The Spielberger State-Trait Anxiety Inventory was administered before obtaining consent (state 1), immediately after the consent protocol (state 2), and after the electrophysiologic testing procedure, when the results of the test were known to the patient (state 3). Midazolam was administered during the procedure by staff who were blinded to the state/trait anxiety scores and the type of consent the patient had received. Patients receiving consent A had a significant decrease in state 2 anxiety compared with those who received consent B (adjusted mean difference 3.3; 95% confidence intervals 0.2 to 6.4). In the consent A group, 74% of patients received midazolam as opposed to 96% in the consent B group (p <0.02). Patients without inducible ventricular arrhythmias had a significant decrease in state 3 anxiety compared with those with inducible ventricular arrhythmias (adjusted mean difference 8.9; 95% confidence intervals 2.3 to 15.5). Thus detailed informed consent is associated with increased anxiety relative to a consent that does not detail specific risks. However, the difference in anxiety is mild and its clinical impact requires further exploration.

The addition of hemiarch replacement to aortic root surgery does not affect safety

OBJECTIVES A hemiarch reconstruction, using deep hypothermic circulatory arrest, is the conventional approach for proximal aortic arch reconstruction, but it carries risks of neurologic events and coagulopathy. The addition of a hemiarch reconstruction to an aortic root replacement may prevent future aortic arch pathology. Outcomes of this approach at a tertiary care institution were examined to determine whether the addition of a hemiarch reconstruction to an aortic root replacement conferred any additional risk. METHODS A total of 384 patients underwent an aortic root replacement between April 2004 and June 2012. Of them, 177 (46%) had hemiarch replacement. Propensity score matching yielded 133 pairs of patients receiving hemiarch and non-hemiarch. RESULTS Sinus segment diameter was similar between groups; ascending aortic diameter was greater in the hemiarch group (median 50 vs 44 mm; P < .001). The hemiarch group had longer perfusion (median 186 vs 120.5 minutes; P < .001) and crossclamp times (median 140 vs 104 minutes; P < .001); median circulatory arrest was 13 minutes. There was no difference, hemiarch versus no hemiarch, in 30-day mortality (3.0% vs 1.5%; P = .41), stroke (2.3% vs 4.5%; P = .31), reoperation for bleeding (11% vs 10%; P = .84), or overall survival (5-year 88.0% [95% confidence interval, 81.9-94.0] vs 91.4% [95% confidence interval, 85.8-96.9], P = .24). CONCLUSIONS In this series, aortic root replacement ± hemiarch reconstruction had low mortality. Addition of hemiarch replacement extended perfusion times but not at the expense of safety. Hemiarch reconstruction should be performed when the aortic root aneurysm extends into the distal ascending aorta.

Detection of atrial fibrillation after surgical ablation: Conventional versus continuous monitoring

BACKGROUND Current guidelines recommend at least 24-hour Holter monitoring at 6-month intervals to evaluate the recurrence of atrial fibrillation (AF) after surgical ablation. In this prospective multicenter study, conventional intermittent methods of AF monitoring were compared with continuous monitoring using an implantable loop recorder (ILR). METHODS From August 2011 to January 2014, 47 patients receiving surgical treatment for AF at 2 institutions had an ILR placed at the time of operation. Each atrial tachyarrhythmia (ATA) of 2 minutes or more was saved. Patients transmitted ILR recordings bimonthly or after any symptomatic event. Up to 27 minutes of data was stored before files were overwritten. Patients also underwent electrocardiography (ECG) and 24-hour Holter monitoring at 3, 6, and 12 months. ILR compliance was defined as any transmission between 0 and 3 months, 3 and 6 months, or 6 and 12 months. Freedom from ATAs was calculated and compared. RESULTS ILR compliance at 12 months was 93% compared with ECG and Holter monitoring compliance of 85% and 76%, respectively. ILR devices reported a total of 20,878 ATAs. Of these, 11% of episodes were available for review and 46% were confirmed as AF. Freedom from ATAs was no different between continuous and intermittent monitoring at 1 year. Symptomatic events accounted for 187 episodes; however, only 10% were confirmed as AF. CONCLUSIONS ILR was equivalent at detecting ATAs when compared with Holter monitoring or ECG. However, the high rate of false-positive readings and the limited number of events available for review present barriers to broad implementation of this form of monitoring. Very few symptomatic events were AF on review.