Chad M. House

Continuing warfarin therapy is superior to interrupting warfarin with or without bridging anticoagulation therapy in patients undergoing pacemaker and defibrillator implantation

BACKGROUND Current guidelines recommend stopping oral anticoagulation and starting bridging anticoagulation with intravenous heparin or subcutaneous enoxaparin when implanting a pacemaker or defibrillator in patients at moderate or high risk for thromboembolic events. A limited body of literature suggests that device surgery without cessation of oral anticoagulation may be feasible. OBJECTIVE The purpose of this study was to evaluate the safety of device surgery in orally anticoagulated patients without interrupting warfarin therapy. METHODS We performed a retrospective study of 459 consecutive patients on chronic warfarin therapy who underwent device surgery from April 2004 to September 2008. Warfarin was continued in 222 patients during the perioperative period. Warfarin was temporarily held and bridging therapy administered in 123 patients. Warfarin was temporarily held without bridging therapy in 114 patients. RESULTS There were no significant differences with regard to age, sex, or risk factors for thromboembolism in the three groups. Patients who continued taking warfarin had a lower incidence of pocket hematoma (P = .004) and a shorter hospital stay (P <.0001) than did patients in the bridging group. Holding warfarin without bridging is associated with a higher incidence of transient ischemic attacks (P = .01). CONCLUSION Temporarily interrupting anticoagulation is associated with increased thromboembolic events, whereas cessation of warfarin with bridging anticoagulation is associated with a higher rate of pocket hematoma and a longer hospital stay. Continuing warfarin with a therapeutic international normalized ratio appears to be a safe and cost-effective approach when implanting a pacemaker or defibrillator in patients with moderate to high thromboembolic risk.

Predictors of inotrope use in patients undergoing concomitant coronary artery bypass graft (CABG) and aortic valve replacement (AVR) surgeries at separation from cardiopulmonary bypass (CPB).

BackgroundLeft ventricular dysfunction is common after coronary artery bypass graft and valve replacement surgeries and is often treated with inotropic drugs to maintain adequate hemodynamic status. In this study, we aimed to identify the demographic, clinical, laboratory, echocardiographic and hemodynamic factors that are associated with use of inotropic drugs in patients undergoing concomitant coronary artery bypass graft and aortic valve replacement surgery.MethodsThe study included 97 patients who had undergone concomitant coronary artery bypass graft and aortic valve replacement at Regions Hospital, University of Minnesota Medical School from January 2006 to December 2008. All data were collected retrospectively after reviewing electronic medical records. Inotropic support was defined as the use of dopamine [greater than or equal to] 5 ug/kg/min; any dose of epinephrine, norepinephrine, dobutamine, and milrinone at the separation from cardiopulmonary bypass.ResultsInotropic support was used in a total of 50 patients (52%) at the separation from cardiopulmonary bypass. Average age of the patients requiring inotropic support was 72.2 +/- 8.8 years. The study identified four significant, independent predictors of inotrope use: (1) Cardiac index [less than or equal to]2.5 L/min/m2, (2) LVEDP [greater than or equal to] 20 mm Hg, (3) LVEF [less than or equal to]40%, and (4) CKD stage 3 to 5.ConclusionWe identified four independent risk factors for postoperative use of inotropic support in patients undergoing concomitant coronary artery bypass graft and arotic valve replacement surgery at the separation from cardiopulmonary bypass. The study results will be helpful to prospectively identify patients who will likely to require inotropic support at the separation from cardiopulmonary bypass.

Mitral valve area by the pressure half-time method does not correlate with mean gradient in mitral valve repair patients.

AIMS Pressure half-time is an inaccurate measure of mitral valve area in many clinical situations. The utility of the pressure half-time method to calculate mitral valve area after mitral valve repair is not well defined. METHODS AND RESULTS Forty-two patients with a repaired mitral valve were identified. Mitral valve area was calculated by both the pressure half-time method and the continuity equation. The two mitral valve areas were then directly compared and also correlated with mean gradient. The two mitral valve areas were significantly different from one another with a mean of 1.81 ± 0.53 cm(2) by continuity equation and 2.65 ± 0.69 cm(2) by pressure half-time. The continuity equation correlated well with mean gradient (ρ = -0.63), whereas the correlation for pressure half-time was weak (r = -0.08). CONCLUSION A non-linear, inverse correlation was found between mitral valve area by the continuity equation and mean gradient. No correlation was found between the pressure half-time method for mitral valve area and mean gradient. The continuity equation likely provides a better estimate of mitral valve area in repaired mitral valves.

Predictors of appropriate therapy in patients with implantable cardioverter-defibrillator for primary prevention of sudden cardiac death.

The purpose of this study was to evaluate predictors of appropriate therapy in patients with implantable cardioverter-defibrillators (ICD) for primary prevention of sudden cardiac death. A retrospective cohort of 321 patients with systolic heart failure undergoing ICD placement for primary prevention of sudden cardiac death was queried with a mean follow-up period of 2.6 years. Appropriate ICD therapy was defined as therapy delivered for termination of a ventricular tachyarrhythmia. Appropriate ICD therapy was delivered in 142 (44%) of the patients. In a multivariate model, body mass index ≥28.8 kg/m2, chronic kidney disease, left ventricular ejection fraction ≤20% and metabolic syndrome were found to be independent predictors of appropriate ICD therapy. Appropriate ICD therapy was associated with higher cardiovascular mortality. These findings show the importance of identification of risk factors, especially metabolic syndrome, in patients following ICD implantation as aggressive treatment of these co-morbidities may decrease appropriate ICD therapy and cardiovascular mortality.

Letter by House et al Regarding Article, “Prosthesis-Patient Mismatch in Bovine Pericardial Aortic Valves: Evaluation Using 3 Different Modalities and Associated Medium-Term Outcomes”

This algorithm was specifically created to assist in the evaluation of aortic prostheses with elevated peak velocities exceeding 3 m/sec. A common pathogenesis of velocities exceeding 3 m/sec is PPM, although this is not the exclusive reason for increased velocities. In addition, PPM is not invariably associated with velocities exceeding 3 m/sec, as demonstrated in low-flow states. These low-flow states can occur with reduced left ventricular ejection fraction (LVEF; ie, classical low-flow) but also with preserved LVEF (paradoxical low-flow). 4 The authors did exclude patients with LVEF <50%, with the goal of creating a hemodynamically similar cohort. However, it has been well established that a normal LVEF is not synonymous with a normal stroke volume, and that a large proportion (10%–35%) of patients with preserved LVEF have in fact reduced transvalvular flow. 4 This paradoxical low-flow state is often associated with pseudonormalization of transvalvular flow velocities and gradients in patients with native aortic valve stenosis, leading to underestimation of stenosis severity. The same concept applies to patients with prosthetic heart valves, such that patients with preserved LVEF who have reduced stroke volume can have PPM even with flow velocities <3 m/sec. Similar to what is observed in patients with paradoxical low-flow, low-gradient aortic stenosis, these patients with preserved LVEF and concomitant low-flow, low-gradient PPM likely have worse prognosis compared with those with normal flow and elevated gradient PPM. Not taking into account this phenomenon of velocity/gradient pseudonormalization associated with paradoxical low-flow obviously led to a significant underestimation of the true incidence of PPM in this series. Although the American Society of Echocardiography guidelines algorithm provides a useful template to guide the investigation of potential pathogeneses of increased transprosthetic velocities, it is unlikely that it was intended for the comprehensive evaluation of PPM. In particular, this algorithm does not address the case of patients with paradoxical low-flow who may exhibit low velocities and gradients despite the presence of significant PPM. Manufacturer-provided effective orifice area index charts have been shown to overestimate EOAs and ultimately underestimate the incidence of PPM. 5

Feasibility of an Elective Cardioversion Service Led by Advanced Practice Providers without Direct Cardiologist Supervision

Background: Elective direct current cardioversion (DCCV) has traditionally been performed by physicians in the United States. A few recent reports from the United Kingdom suggested that a specialist nurse-led service for elective DCCV of persistent atrial fibrillation was feasible. This practice has not been reported in the United States previously. Several years ago, we introduced a program where specially trained advanced practice providers (APPs) (physician assistants and nurse practitioners) assisted by an anesthesiology team, performed elective DCCV in patients with atrial fibrillation and atrial flutter, without direct cardiologist supervision. Methods: Upon receiving approval from the Institutional Review Board, we conducted a retrospective analysis of 447 consecutive DCCVs electively performed by APPs, for atrial fibrillation or atrial flutter, at Regions Hospital between 12/2006 and 10/2010. Transient deep sedation was administered by an anesthesiology team. The cohort was evaluated for procedural success and safety. Results: The procedural success rate was 92% (412/447). The incidence of procedural related adverse events, requiring immediate intervention, was 0.2% (1/447). This patient required emergent temporary pacing catheter insertion followed by a permanent pacemaker implantation at a later date. There were no other procedure-related complications and no thromboembolic events. A comparison with fifty elective cardioversions performed by cardiologists during the same period found no statistical difference in procedural success rates or complications. Conclusion: Under deep sedation administered by anesthesiology service, elective DCCV of atrial fibrillation and atrial flutter performed by well-trained APPs, without direct cardiologist supervision, is feasible and does not compromise patient safety.

The Association Between Cardiac Rehabilitation Attendance and Hospital Readmission

Purpose: Cardiac rehabilitation is associated with improved clinical outcomes, but the impact of individual cardiac rehabilitation sessions on readmission rates is less studied. Methods: A retrospective evaluation of the relationship between the number of cardiac rehabilitation sessions completed and all-cause and cardiac readmission rates at 1 year was conducted. The 1-year cardiac readmission counts were modeled via Poisson regression. Results: Of the 347 patients included in the primary analysis, 227 (65%) completed all assigned cardiac rehabilitation sessions. At 1 year, 135 patients (39%) had at least 1 cardiac readmission, and 155 patients (45%) had at least 1 all-cause readmission. The primary result was that every additional cardiac rehabilitation session completed was associated with a 1.75% lower incidence rate of 1-year cardiac readmission (P = .01) and a 2% lower incidence rate of all-cause hospital readmission (P = .001). Conclusion: Regardless of the number of cardiac rehabilitation sessions assigned, each additional session attended was associated with reduced cardiac readmission by 1.75% and all-cause readmission by 2%.

Sudden cardiac arrest in apical hypertrophic cardiomyopathy

We present two cases of cardiac arrest, presumably attributable to apical hypertrophic cardiomyopathy(HCM). The first case was a 37-year-old Asian man known to have an apical HCM and was successfully resuscitated from an “out of hospital” ventricular fibrillation arrest. He underwent an electrophysiological study that was unable to induce tachyarrhythmias, which may not be surprising. He did receive an automated internal cardioverter defibrillator (AICD) in compliance with his class I indication for an implantable defibrillator. The second patient was an 86-year-old Caucasian woman with a cardiac history significant for apical HCM, coronary artery disease, diastolic heart failure, and monomorphic ventricular tachycardia. She underwent electrophysiological testing for frequent dizziness and monomorphic ventricular tachycardia of a right ventricular origin was induced. She received an AICD for sudden cardiac death prevention. Though lethal ventricular arrhythmias have been reported in patients with apical HCM, the prevailing consensus is that the prognosis of apical HCM is benign. Whether these accounts are truly exceptional occurrences for this rare and conventionally regarded benign condition or whether they represent an under-appreciated risk for sudden cardiac arrest is an intriguing question.

Acute coronary thrombosis in a patient with septic shock without any evidence of disseminated intravascular coagulation.

The case report describes an interesting and unusual finding of acute coronary artery thrombosis in a patient presenting with septic shock without any clinical and laboratory evidence of disseminated intravascular coagulation (DIC). The patient presented with leucocytosis and refractory hypotension requiring pressor support and found to have anterior and inferior ST-elevation in 12-lead electrocardiogram. Coronary angiogram revealed acute thrombotic occlusions in the proximal right coronary artery and the proximal left anterior descending coronary artery. There was no occlusive atherosclerotic coronary artery disease. The patient underwent mechanical thrombectomy. Haemodynamic parameters obtained from right heart catheterisation confirmed sepsis as the aetiology of hypotension. The patient was treated successfully with broad spectrum antibiotics, pressors and intravenous fluid. Acute myocardial infarctions as a complication secondary to disseminated intravascular coagulation in patients with sepsis and septic shock have been described in the literature. To our knowledge, this is the first reported case of acute coronary artery thrombosis in patient with septic shock without DIC and without any underlying occlusive coronary artery disease.