Erroneous electrocardiographic interpretations and its clinical implications.

INTRODUCTION: The advancement of artificial intelligence (AI) has aided clinicians in the interpretation of electrocardiograms (ECGs) serving as an essential tool to provide rapid triage and care. However, in some cases, AI can misinterpret an ECG and may mislead the interpreting physician. Therefore, we aimed to describe the rate of ECG misinterpretation and its potential clinical impact in patient's management. METHODS: We performed a retrospective descriptive analysis of misinterpreted ECGs and its clinical impact from May 28, 2020 to May 9, 2021. An electrophysiologist screened ECGs with confirmed diagnosis of atrial fibrillation (AF), sinus tachycardia (ST), sinus bradycardia (SB), intraventricular conduction delay (IVCD), and premature atrial contraction (PAC) that were performed in the emergency department. We then classified the misinterpreted ECGs as wrongly diagnosed AF, ST, SB, IVCD, or PAC into the correct diagnosis and reviewed the misinterpreted ECGs and medical records to evaluate inappropriate use of antiarrhythmic drugs (AAD), beta-blockers (BB), calcium channel blockers (CCB), anticoagulation, or resource utilization of cardiology and/or electrophysiology (EP) consultation. RESULTS: A total of 4969 ECGs were screened with diagnoses of AF (2282), IVCD (296), PAC (972), SB (895), and ST (638). Among these, 101 ECGs (2.0%) were misinterpreted. Wrongly diagnosed AF (58.4%) was the most common followed by wrongly diagnosed PAC (14.9%), wrongly diagnosed ST (12.9%), wrongly diagnosed IVCD (7.9%), and wrongly diagnosed SB (6.0%). Patients with misinterpreted ECGs were aged 76.6 ± 11.6 years with male (52.5%) predominance and hypertension being the most prevalent (83.2%) comorbid condition. The misinterpretation of ECGs led to the inappropriate use of BB (19.8%), CCB (5.0%), AAD therapy (7.9%), anticoagulation (6.9%) in patients with wrongly diagnosed AF, as well as inappropriate resource utilization including cardiology (41.6%) and EP (8.9%) consultations. CONCLUSIONS: Misinterpretation of ECGs may lead to inappropriate medical therapies and increased resource utilization. Therefore, it is essential to encourage physicians to carefully examine AI interpreted ECG's, especially those interpreted as having AF.

The Arrhythmogenicity of Sotalol and its Role in Heart Failure: A Literature Review.

ABSTRACT: According to the American Heart Association, approximately 6 million adults have been afflicted with heart failure in the United States in 2020 and are more likely to have sudden cardiac death accounting for approximately 50% of the cause of mortality. Sotalol is a nonselective ß-adrenergic receptor antagonist with class III antiarrhythmic properties that has been mostly used for atrial fibrillation treatment and suppressing recurrent ventricular tachyarrhythmias. The use of sotalol in patients with left ventricular dysfunction is not recommended by the American College of Cardiology or American Heart Association because studies are inconclusive with conflicting results regarding safety. This article aims to review the mechanism of action of sotalol, the ß-blocking effects on heart failure, and provide an overview of clinical trials on sotalol use and its effects in patients with heart failure. Small- and large-scale clinical trials have been controversial and inconclusive about the use of sotalol in heart failure. Sotalol has been shown to reduce defibrillation energy requirements and reduce shocks from implantable cardioverter-defibrillators. Torsades de Pointes is the most life-threatening arrhythmia that has been documented with sotalol use and occurs more commonly in women and heart failure patients. Thus far, mortality benefits have not been demonstrated with sotalol use and larger multicenter studies are required going forward.

Do ICD diagnostics predict failure of ventricular tachycardia response to antitachycardia pacing and need for shock?

BACKGROUND: Among heart failure patients with implantable cardioverter defibrillators (ICDs), monomorphic ventricular tachycardia (MMVT) failing antitachycardia pacing (ATP) and terminated by shock renders higher mortality as compared to MMVT terminated by ATP only. It is unknown if the higher mortality in ATP failure reflects decompensated heart failure. OBJECTIVE: It was the purpose of the present study to determine if ICD heart failure diagnostics can predict the failure of ATP and the need to shock to terminate MMVT. METHODS: This was a single-center retrospective review of 103 consecutive patients with Medtronic ICDs who had MMVT and received ICD therapy. Heart failure diagnostics preceding each MMVT event were reviewed including atrial fibrillation burden, patient activity, night heart rate, heart rate variability, Optivol® fluid index, and MMVT heart rate. RESULTS: A total of 452 MMVT events were analyzed, of which 23% required shock. Compared to MMVT that responded to ATP, MMVT that failed ATP and required shock had significantly faster heart rates and higher atrial fibrillation burden. Patient activity, night heart rate, heart rate variability, and OptiVol® fluid index were similar between ATP responsive MMVT events and those that failed ATP. In a multivariate analysis adjusting for baseline characteristics, higher atrial fibrillation burden and lower patient activity were associated with ATP failure and shock termination. CONCLUSION: Device diagnostics associated with decompensated heart failure identified MMVT events that failed ATP and necessitated shock.

Clinical predictors of antitachycardia pacing response in implantable cardioverter defibrillator patients.

BACKGROUND: Antitachycardia pacing (ATP) provides safe and painless termination of reentrant ventricular arrhythmias in patients with implantable cardioverter defibrillator (ICDs), improving their quality of life. Established predictors of ATP responsiveness are not well known; only longer ventricular tachycardia (VT) cycle length and higher ejection fraction have been found to predict ATP success. OBJECTIVE: To investigate clinical and ECG predictors of ATP response in ICD patients with monomorphic VT. METHODS: The ICD clinic database was searched for monomorphic VT events requiring ICD therapy in patients with ischemic or non-ischemic cardiomyopathy. Each patient's first ICD encounter for VT was assessed. Patient demographics, clinical characteristics, VT rate, and ATP responsiveness (always, sometimes, and never successful) were recorded. An ECG was analyzed for QRS morphology and duration. Data was assessed for predictors of ATP responsiveness. RESULTS: In 527 patients, characteristics associated with always successful ATP included ACE-I/ARB therapy and slower VT rate (never successful ATP 197 ± 28 bpm, sometimes successful ATP 190 ± 27 bpm, always successful ATP 183 ± 22 bpm, P < .0001). Secondary prevention indication, amiodarone therapy, and longer QRS duration were associated with ATP failure. After multivariate analysis, only faster VT rate and amiodarone therapy were predictive of ATP failure. CONCLUSIONS: Neither QRS morphology nor duration was predictive of ATP success. Slower VT rate was predictive of repeated ATP responsiveness. Amiodarone therapy, which is known to increase VT cycle length, interestingly was associated with ATP failure for unclear reasons. More individualized and possibly more aggressive ATP programming may be warranted in patients on amiodarone.

Ventricular electrical delay as a predictor of arrhythmias in patients with cardiac resynchronization implantable cardioverter defibrillator.

BACKGROUND: Left ventricular (LV) remodeling and clinical response to cardiac resynchronization therapy (CRT) is inversely related to electrical dyssynchrony, measured as LV lead electrical delay (QLV). Presence of atrial or ventricular arrhythmia is correlated with worsening heart failure and LV remodeling. OBJECTIVE: We sought to assess the association of QLV with arrhythmic events in CRT recipients. METHODS: We identified patients implanted with a CRT device at our center. QLV interval was measured and corrected for baseline QRS (cQLV). We performed multivariable Logistic regression to assess the effect of cQLV on the occurrence of atrial/ventricular arrhythmic events. RESULTS: Sixty-nine patients were included in analyses. The cQLV was significantly shorter in patients with atria tachycardia/supraventricular tachycardia (AT/SVT) events compared to patients without AT/SVT events (43.4 ± 22% vs. 60.3 ± 26.7%, p = .006). In contrast, no significant difference in cQLV was observed between patients with and without ventricular tachycardia/fibrillation (VT/VF) events (46.2 ± 25.4% vs. 56 ± 25.7%, p = .13). cQLV was significantly shorter in patients with new onset AT/SVT events compared to those without (38.3 ± 22.2% vs. 55.7 ± 25.7%, p = .028). In contrast, no significant difference in cQLV was observed between patients with and without new onset VT/VF events (44.2 ± 25.2% vs. 56.3 ± 25.5%, p = .069). Following adjusted analyses, cQLV was a significant predictor of AT/SVT, but not for VT/VF. CONCLUSION: cQLV is a simple measure that can identify a vulnerable cohort of CRT patients at increased risk for atrial tachyarrhythmias, and hence can predict reverse remodeling and clinical response to CRT treatment.

Vitamin K antagonist use: evidence of the difficulty of achieving and maintaining target INR range and subsequent consequences.

Vitamin K antagonists (VKAs) are effective oral anticoagulants that are titrated to a narrow therapeutic international normalized ratio (INR) range. We reviewed published literature assessing the impact of INR stability - getting into and staying in target INR range - on outcomes including thrombotic events, major bleeding, and treatment costs, as well as key factors that impact INR stability. A time in therapeutic range (TTR) of ≥65 % is commonly accepted as the definition of INR stability. In the real-world setting, this is seldom achieved with standard-of-care management, thus increasing the patients' risks of thrombotic or major bleeding events. There are many factors associated with poor INR control. Being treated in community settings, newly initiated on a VKA, younger in age, or nonadherent to therapy, as well as having polymorphisms of CYP2C9 or VKORC1, or multiple physical or mental co-morbid disease states have been associated with lower TTR. Clinical prediction tools are available, though they can only explain <10 % of the variance behind poor INR control. Clinicians caring for patients who require anticoagulation are encouraged to intensify diligence in INR management when using VKAs and to consider appropriate use of newer anticoagulants as a therapeutic option.

Ranolazine Therapy in Cardiac Arrhythmias.

Ranolazine is an antianginal medication originally granted approval by the U.S. Food and Drug Administration for therapeutic use in 2006. Since its introduction into the U.S. market, there have been multiple trials and clinical case reports that demonstrate ranolazine may be effective in the prevention and treatment of both atrial and ventricular arrhythmias, including postoperative atrial fibrillation following coronary artery bypass graft (CABG) surgery. More recently, the combination of dronedarone with ranolazine has demonstrated in initial studies to have a synergistic effect in the reduction of burden of atrial fibrillation. This article will review the basic pharmacology of ranolazine, the studies demonstrating use of ranolazine in atrial and ventricular arrhythmias, the limitations to the use of ranolazine as antiarrhythmic therapy, and explore the synergistic effect with other agents in the suppression of arrhythmias.

Late Gadolinium Enhancement in Patients with Nonischemic Dilated Cardiomyopathy.

One-third of all patients with heart failure have nonischemic dilated cardiomyopathy (NIDM). Five-year mortality from NIDM is as high as 20% with sudden cardiac death (SCD) as the cause in 30% of the deaths. Currently, the left ventricular ejection fraction (LVEF) is used as the main criteria to risk stratify patients requiring an implantable cardioverter defibrillator (ICD) to prevent SCD. However, LVEF does not necessarily reflect myocardial propensity for electrical instability leading to ventricular tachycardia (VT) or ventricular fibrillation (VF). Due to the differential risk in various subgroups of patients for arrhythmic death, it is important to identify appropriate patients for ICD implantation so that we can optimize healthcare resources and avoid the complications of ICDs in individuals who are unlikely to benefit. We performed a systematic search and review of clinical trials of NIDM and the use of ICDs and cardiac magnetic resonance imaging with late gadolinium enhancement (LGE) for risk stratification. LGE identifies patients with NIDM who are at high risk for SCD and enables optimized patient selection for ICD placement, while the absence of LGE may reduce the need for ICD implantation in patients with NIDM who are at low risk for future VF/VT or SCD.

Corrected QT in ventricular paced rhythms: what is the validation for commonly practiced assumptions?

INTRODUCTION: Ventricular pacing (VP) may impact the accuracy of QT interval measurement, as it increases the QT by increasing the QRS duration amongst other mechanisms. We aimed to investigate the accuracy of the commonly used clinical practice of subtracting 50 ms from the corrected QT (QTc) in ventricular paced rhythms. METHODS: We conducted a prospective observational study on 23 consecutive pacemaker patients. Four ECGs were recorded for each subject, 2 in their native rate and 2 following an atrial paced, atrial sensed and inhibited response to sensing and then a dual pacing, dual sensing and dual response pacing of 100 bpm to allow for an intrinsic and a ventricular paced QRS, respectively. The averaged QTc in the ventricular paced rhythm was then compared with the non-ventricular-paced QTc for individual subjects. RESULTS: At a mean spontaneous heart rate of 66 bpm (SD ±8), the mean difference in QTc between the ventricular paced and nonpaced QRS was 48.27 ms (95% CI = 32-64.6 ms, p < 0.001). At faster paced rates, the mean QTc difference was 81.3 ms (95% CI = 35.8-126.8 ms, p = 0.002). CONCLUSIONS: The QTc measurement during VP confirms the current 50-ms subtraction assumption rule within a range of ±16 ms at an average heart rate of 66 bpm. However, at faster heart rates, the 50-ms adjustment may underestimate the QTc discrepancy between a wide and normal QRS.

A tale of two syndromes: Lyme disease preceding postural orthostatic tachycardia syndrome.

The pathogenesis of postural orthostatic tachycardia syndrome (POTS) is poorly understood. However, it has been suggested that altered immune activity or denervation of the autonomic system following illness may be an important trigger. Patients infected with Lyme disease have a small incidence of post-Lyme disease syndrome that share similar characteristics to POTS. We report a short series of two women who present with persistent symptoms of orthostatic intolerance consistent with POTS after treated Lyme disease.

An Adverse Electrophysiological Interaction Between an Implantable Cardioverter-Defibrillator and a Ventricular Assist Device.

Many patients with left ventricular assist devices (LVAD) have implantable cardioverter defibrillators (ICDs) as part of the management of advanced heart failure. With increasing use and coexistence of these devices in patients with advanced cardiomyopathy, adverse interactions between these devices have been recognized. We herewith describe a rare adverse interaction of electromagnetic interference (EMI) between a third-generation, continuous-flow device (The HeartWare HVAD) and an ICD which resulted in the delivery of inappropriate ICD therapies. A schematic approach for the prevention and treatment of electromagnetic interference has also been described.

PYREXIA-INDUCED BRUGADA PHENOCOPY.

Brugada syndrome (BS) is characterized by a typical electrocardiographic (ECG) pattern in the right precordial leads and a predisposition to develop ventricular arrhythmias. Mutations in a subunit of cardiac sodium channel (SCN5A) have been linked to BS. Experimental studies in the literature suggest that this dysfunction of the mutated channel can be temperature sensitive. Several antiarrhythmics have been used in the management of BS but Implantable Cardioverter Defibrillators (ICD) remains the only effective treatment. We herewith present the case report of a 62-year-old man who developed a type-2 Brugada ECG phenotype in a febrile state with complete resolution once the fever subsided.

The prognostic impact of pre-implantation hyponatremia on morbidity and mortality among patients with left ventricular dysfunction and implantable cardioverter-defibrillators.

AIMS: Hyponatremia is commonly observed among patients with left ventricular (LV) dysfunction and is a marker for adverse outcomes. We aimed to determine the prognostic significance of pre-implant hyponatremia on the outcomes of death, acute decompensated heart failure (ADHF) and appropriate implantable cardioverter-defibrillator (ICD) therapy for ventricular arrhythmias among patients with ICDs. METHODS AND RESULTS: The study population consisted of patients with an ejection fraction ≤40% undergoing ICD implantation (n = 911) for the primary or secondary prevention of sudden cardiac death from 1997 to 2007. The predictive value of the severity of pre-implantation hyponatremia stratified into mild hyponatremia (n = 268, sodium 134-136 mmol/L), moderate hyponatremia (n = 105, sodium 131-133 mmol/L), and severe hyponatremia (n = 31, sodium ≤130 mmol/L) on the risk of death, ADHF, and appropriate ICD therapy for ventricular arrhythmias as compared with patients a normal serum sodium (n = 507, sodium ≥ 137 mmol/L), was calculated using multivariable Cox proportional hazards analyses. During a mean follow-up of 775 ± 750 days as the severity of hyponatremia (from a normal sodium to severe hyponatremia) increased an incremental incidence of death (25% to 61%, P < 0.001) and ADHF (11% to 26%, P = 0.004) was observed with a reduced incidence of ICD therapy for ventricular tachycardia/ventricular fibrillation (37-29%, P = 0.037). Compared with the normal sodium cohort, patients with severe hyponatremia demonstrated an increased risk of death [adjusted hazard ratio (AHR) 2.69 (95% confidence interval, CI 1.57-4.59), P = 0.004] and ADHF [AHR 2.98 (95% CI 1.41-6.30), P = 0.004], with a lower probability of appropriate ICD therapy [AHR 0.68 (95% CI 0.27-0.88), P = 0.031]. CONCLUSION: Hyponatremia is commonly observed among ICD recipients with LV dysfunction. Patients with an increasing severity of hyponatremia are at increased risk of death and HF related morbidity with a reduced incidence of appropriate ICD therapy particularly among patients with severe hyponatremia.

The healthcare utilization and cost of treating patients experiencing inappropriate implantable cardioverter defibrillator shocks: a propensity score study.

BACKGROUND: Inappropriate shocks (IASs) from implantable cardioverter defibrillators (ICDs) are associated with decreased quality of life, but whether they increase healthcare utilization and treatment costs is unknown. We sought to determine the impact of IASs on subsequent healthcare utilization and treatment costs. METHODS: We conducted a case-control analysis of ICD patients at a single institution from 1997 to 2010 and who had ≥12 months of post-ICD implant follow-up. Cases included all patients experiencing an IAS during the first 12 months after implantation. Eligible control patients did not receive a shock of any kind during the 12 months after implantation. Propensity scores based on 36 covariates (area under curve = 0.78) were used to match cases to controls. We compared the rate (occurrences/person year [PY]) of healthcare utilization immediately following IAS to the end of the 12-month follow-up period to the rate in the no-shock group over 12 months of follow-up. We also compared 12-month postimplant treatment (outpatient clinic, emergency room, and hospitalization) costs in both groups. RESULTS: A total of 76 patients experiencing ≥1 IAS during the first 12 months after implant (contributing 48 PYs) were matched to 76 no-shock patients (contributing 76 PYs). Cardiovascular (CV)-related clinic visit and hospitalization rates were increased following an IAS compared to those not receiving a shock (4.0 vs 3.3 and 0.7 vs 0.5, respectively, P = 0.02 for both). CV-related emergency room visitation (0.15 vs 0.08) rates were also numerically higher following an IAS, but did not reach statistical significance (P = 0.26). Patients experiencing an IAS accrued greater treatment costs during the 12 months postimplant compared to no-shock patients ($13,973 ± $46,345 vs $6,790 ± $19,091, P = 0.001). CONCLUSION: Recipients of IAS utilize the healthcare system more frequently following an IAS than patients not experiencing a shock. This increased utilization results in higher costs of treating IAS patients during the 12 months postimplant.

Transient high-grade atrioventricular block in an orthotopic cardiac transplant recipient.

A 56-year-old male with a history of orthotopic cardiac transplantation secondary to cardiac sarcoidosis presented with recurrent episodes of syncope preceded by dizziness. While on telemetry, he had transient episodes of high-grade atrioventricular (AV) block that reproduced his prodrome. After excluding allograft rejection, ischemia, recurrent cardiac sarcoidosis, and vagally mediated block as a cause of high-grade AV block, adenosine testing was done which reproduced the spontaneous high-grade AV block. We concluded that hypersensitivity to endogenously released adenosine was the likely mechanism of AV block in our patient. This is the first reported case of adenosine testing in a cardiac transplant patient for diagnosing episodic high-degree AV block of unclear etiology.

Magnesium adjunctive therapy in atrial arrhythmias.

Magnesium (Mg) is an important intracellular ion with cardiac metabolism and electrophysiologic properties. A large percentage of patients with arrhythmias have an intracellular Mg deficiency, which is out of line with serum Mg concentrations, and this may explain the rationale for Mg's benefits as an atrial antiarrhythmic agent. A current limitation of antiarrhythmic therapy is that the potential for cardiac risk offsets some of the benefits of therapy. Mg enhances the balance of benefits to harms by enhancing atrial antiarrhythmic efficacy and reducing antiarrhythmic proarrhythmia potential as well as providing direct antiarrhythmic efficacy when used as monotherapy in patients undergoing cardiothoracic surgery.

Predictors of pacemaker dependence and pacemaker dependence as a predictor of mortality in patients with implantable cardioverter defibrillator.

BACKGROUND: The prevalence, predictors, and survival for the development of pacemaker dependence (PD) in patients implanted with an implantable cardioverter defibrillator (ICD) are unknown. METHODS: This was a retrospective analysis of 1,550 consecutive patients with ICD implantation at a single center from 1996 to 2008 with a mean of 4.2 ± 3.4 years. Patients with implant intrinsic heart rates less than 40 beats/min (n = 48) and cardiac resynchronization therapy (n = 444) were excluded leaving 1,058 patients in this study. PD was defined as an intrinsic rhythm <40 beats/min after inhibiting the pacemaker, <50 beats/min with transient symptoms of dizziness relieved by resumption of pacing and right ventricle pacing despite algorithms to promote intrinsic conduction at the 3 monthly follow-up ICD clinic visits. Multivariate regression and Cox proportional hazard models were used for analysis. RESULTS: The mean age was 64 ± 13 years; 79% were male with a primary indication for the ICD in 57%. PD occurred in 142 (13.4%) of patients, with a mean time to PD of 2.6 ± 1.9 years. PD was associated with a 48% increased odds for mortality versus non-PD ICD patients during the mean follow-up time of 4.2 ± 3.4 years (adjusted odds ratio = 1.48 [95% confidence interval 1.080-2.042]; P = 0.015). Older age, a history of atrial fibrillation, amiodarone use, and secondary prevention were the strongest predictors for the development of PD. CONCLUSIONS: In this single-center ICD cohort, the development of PD was not uncommon and was associated with decreased survival.

Evaluation of the Charlson comorbidity index to predict early mortality in implantable cardioverter defibrillator patients.

BACKGROUND: Current guidelines consider the implantation of an implantable cardioverter defibrillator (ICD) a class III indication in patients with a life expectancy of <1 year. An evaluation of concomitant noncardiac conditions may identify patients whom may not derive benefit with ICD therapy. We sought to evaluate the association of the Charlson comorbidity index (CCI) on the prediction of early mortality (EM), death <1 year after ICD implant. METHODS: The study population consisted of patients (n = 1062) undergoing ICD implantation for the primary or secondary prevention of sudden cardiac death from 1997 to 2007. The predictive value of the CCI on the risk of EM and appropriate shock therapy for ventricular arrhythmias as compared to patients without EM after ICD implant was calculated using multivariable Cox proportional hazards and receiver operator analyses. RESULTS: Patients experiencing EM (n = 110) demonstrated higher CCI scores (mean 2.8 ± 1.3 vs 1.5 ± 1.2, P < 0.001) as compared to individuals without EM (n = 963). Among patients with a CCI of 0, 1, 2, 3, 4, and ≥5, the incidence of EM increased from 5% to 78%. The CCI was an independent predictor of EM (AHR 1.4 [95% CI 1.2-1.6], P < 0.001, per single score increase). Patients who experienced EM demonstrated a decreased incidence of appropriate ICD therapy when compared to patients without EM (AHR 0.4 [95% CI 0.2-0.7], P = 0.001). CONCLUSION: Noncardiac conditions are commonly observed among patients undergoing ICD implantation. Guidelines must incorporate a comprehensive assessment of concomitant comorbidities to minimize the risk of EM and to maximize the survival benefit with ICD therapy.

Prolonged versus standard-duration venous thromboprophylaxis in major orthopedic surgery: a systematic review.

BACKGROUND: The optimal duration of thromboprophylaxis after major orthopedic surgery is unclear. PURPOSE: To compare the benefits and harms of prolonged versus standard-duration thromboprophylaxis after major orthopedic surgery in adults. DATA SOURCES: Cochrane Central Register of Controlled Trials and Scopus from 1980 to July 2011 and MEDLINE from 1980 through November 2011, without language restrictions. STUDY SELECTION: Randomized trials reporting thromboembolic or bleeding outcomes that compared prolonged (≥21 days) with standard-duration (7 to 10 days) thromboprophylaxis. DATA ABSTRACTION: Two independent reviewers abstracted data and rated study quality and strength of evidence. DATA SYNTHESIS: Eight randomized, controlled trials (3 good-quality and 5 fair-quality) met the inclusion criteria. High-strength evidence showed that compared with standard-duration therapy, prolonged prophylaxis resulted in fewer cases of pulmonary embolism (PE) (5 trials; odds ratio [OR], 0.14 [95% CI, 0.04 to 0.47]; absolute risk reduction [ARR], 0.8%), asymptomatic deep venous thrombosis (DVT) (4 trials; relative risk [RR], 0.48 [CI, 0.31 to 0.75]; ARR, 5.8%), symptomatic DVT (4 trials; OR, 0.36 [CI, 0.16 to 0.81]; ARR, 1.5%), and proximal DVT (6 trials; RR, 0.29 [CI, 0.16 to 0.52]; ARR, 7.1%). Moderate-strength evidence showed fewer symptomatic objectively confirmed episodes of venous thromboembolism (4 trials; RR, 0.38 [CI, 0.19 to 0.77]; ARR, 5.7%), nonfatal PE (4 trials; OR, 0.13 [CI, 0.03 to 0.54]; ARR, 0.7%), and DVT (7 trials; RR, 0.37 [CI, 0.21 to 0.64]; ARR, 12.1%) with prolonged prophylaxis. High-strength evidence showed more minor bleeding events with prolonged prophylaxis (OR, 2.44 [CI, 1.41 to 4.20]; absolute risk increase, 6.3%), and insufficient evidence from 1 trial on hip fracture surgery suggested more surgical-site bleeding events (OR, 7.55 [CI, 1.51 to 37.64]) with prolonged prophylaxis. LIMITATIONS: Data relevant to knee replacement or hip fracture surgery were scant and insufficient. Most trials had few events; the strength of evidence ratings that were used may not adequately capture uncertainty in such situations. CONCLUSION: Prolonged prophylaxis decreases the risk for venous thromboembolism, PE, and DVT while increasing the risk for minor bleeding in patients undergoing total hip replacement.

Physical activity is associated with positive responses during carotid sinus massage and head-up tilt-table test in patients with unexplained syncope.

AIMS: Physical exercise is known to alter the physiological response to orthostatic stress. This study compared reported physical activity levels in patients with unexplained syncope who did or did not demonstrate positive responses to carotid sinus massage and head-up tilt-table testing. METHODS: We reviewed the records of 1,336 patients with unexplained syncope who underwent carotid sinus massage and head-up tilt-table testing. Patients with positive responses (cases) were compared with patients with negative responses (controls). Multivariable regression analysis was used to identify independent predictors of positive responses to carotid sinus massage and head-up tilt-table testing. RESULTS: Seventy patients had a positive response to carotid sinus massage and 564 patients had a positive response to head-up tilt-table testing. Physical activity was an independent positive predictor of a positive response to both carotid sinus massage {adjusted odds ratio (AOR) 1.86, 95% CI (1.14-3.05); p = 0.01} and head-up tilt-table testing {AOR 1.31, 95% CI (1.04-1.65); P = 0.02} even after adjustment for multiple other factors including age, gender, and other medical conditions. CONCLUSION: Physical activity is associated with greater likelihood of positive responses during carotid sinus massage and head-up tilt-table testing.