John M. Fontaine

Microvolt T-Wave Alternans Distinguishes Between Patients Likely and Patients Not Likely to Benefit From Implanted Cardiac Defibrillator Therapy A Solution to the Multicenter Automatic Defibrillator Implantation Trial (MADIT) II Conundrum

Background—In 2003, the Centers for Medicaid and Medicare Services recommended QRS duration as a means to identify MADIT II–like patients suitable for implanted cardiac defibrillator (ICD) therapy. We compared the ability of microvolt T-wave alternans and QRS duration to identify groups at high and low risk of dying among heart failure patients who met MADIT II criteria for ICD prophylaxis. Methods and Results—Patients with MADIT II characteristics and sinus rhythm had a microvolt T-wave alternans exercise test and a 12-lead ECG. Our primary end point was 2-year all-cause mortality. Of 177 MADIT II–like patients, 32% had a QRS duration >120 ms, and 68% had an abnormal (positive or indeterminate) microvolt T-wave alternans test. During an average follow-up of 20±6 months, 20 patients died. We compared patients with an abnormal microvolt T-wave alternans test to those with a normal (negative) test, and patients with a QRS >120 ms with those with a QRS ≤120 ms; the hazard ratios for 2-year mortality were 4.8 (P=0.020) and 1.5 (P=0.367), respectively. The actuarial mortality rate was substantially lower among patients with a normal microvolt T-wave alternans test (3.8%; 95% confidence interval: 0, 9.0) than the mortality rate in patients with a narrow QRS (12.0%; 95% confidence interval: 5.6, 18.5). The corresponding false-negative rates are 3.5% and 10.2%, respectively. Conclusion—Among MADIT II–like patients, a microvolt T-wave alternans test is better than QRS duration at identifying a high-risk group and also better at identifying a low-risk group unlikely to benefit from ICD therapy.

Percutaneous pacemaker and implantable cardioverter-defibrillator lead extraction in 100 patients with intracardiac vegetations defined by transesophageal echocardiogram.

OBJECTIVES We describe the feasibility, safety, and clinical outcomes of percutaneous lead extraction in patients at a tertiary care center who had intracardiac vegetations identified by transesophageal echocardiogram. BACKGROUND Infection in the presence of intracardiac devices is a problem of considerable morbidity and mortality. Patients with intracardiac vegetations are at high risk for complications related to extraction and protracted clinical courses. Historically, lead extraction in this cohort has been managed by surgical thoracotomy. METHODS We analyzed percutaneous lead extractions performed from January 1991 to September 2007 in infected patients with echocardiographic evidence of intracardiac vegetations, followed by a descriptive and statistical analysis. RESULTS A total of 984 patients underwent extraction of 1,838 leads; local or systemic infection occurred in 480 patients. One hundred patients had intracardiac vegetations identified by transesophageal echocardiogram, and all underwent percutaneous lead extraction (215 leads). Mean age was 67 years. Median extraction time was 3 min per lead; median implant duration was 34 months. During the index hospitalization, a new device was implanted in 54 patients at a median of 7 days after extraction. Post-operative 30-day mortality was 10%; no deaths were related directly to the extraction procedure. CONCLUSIONS Patients with intracardiac vegetations identified on transesophageal echocardiogram can safely undergo complete device extraction using standard percutaneous lead extraction techniques. Permanent devices can safely be reimplanted provided blood cultures remain sterile. The presence of intracardiac vegetations identifies a subset of patients at increased risk for complications and early mortality from systemic infection despite device extraction and appropriate antimicrobial therapy.

Axillary subpectoral approach for pacemaker or defibrillator implantation in patients with ipsilateral prepectoral infection and limited venous access

PurposeThe prepectoral approach is the procedure of choice for pacemaker or defibrillator (device) implantation. Epicardial or transiliac approaches are reserved for patients in whom the pectoral approach is not feasible. We studied the viability of the axillary subpectoral approach for implanting devices in patients in whom the standard prepectoral approach was not feasible.MethodsDevices and leads were extracted from 16 patients with infected devices in the prepectoral position. The contralateral site was unsuitable for reimplantation because of infection or inadequate venous access. On the side ipsilateral to that with prior prepectoral device infection, we made an incision on the anterior axillary line along the border of the pectoralis major; dissection was continued below the muscle to create a pocket for generator implantation. Axillary venous puncture was performed from the axillary incision and beneath the pectoralis major muscle using a long 14-gauge needle. Long guidewires and peel-away sheaths were used for positioning the lead. The generator was placed in the subpectoral pocket; the wound was closed with absorbable sutures.ResultsOne patient developed a pocket hematoma; one developed a pneumothorax; no other surgical complication, lead malfunction, or recurrence of infection was observed.ConclusionThe axillary subpectoral approach is an acceptable, technically feasible method for reimplantation for patients with pectoral device infection and limited venous access options. It offers the advantage of a new sterile fascial plane ipsilateral to the site of prepectoral device infection.

Clinical Assessment of the Risk for Sudden Cardiac Death in Patients with Sickle Cell Anemia

BACKGROUND Previous studies suggest that patients with sickle cell anemia (SCA) have an increased risk of sudden cardiac death; however, its etiology and mechanism are not well defined. Left ventricular hypertrophy (LVH), ventricular tachycardia (VT) and poor left ventricular systolic function are known risk factors for sudden cardiac death. An abnormal microvolt T-wave alternans (TWA) test is also a predictor of sudden cardiac death risk, but it has not been applied to this patient population. METHODS We performed a 12-lead electrocardiogram, 24-hour Holter monitor, two-dimensional echocardiogram, nuclear stress test and microvolt TWA test to determine whether markers of sudden cardiac death could be identified. RESULTS Twenty-six patients were evaluated with a mean age of 40 +/- 12 years. The two-dimensional echocardiogram revealed a normal ejection fraction in 23 patients and LVH in 17 (65%), whereas hypertension was noted in only five (19%). Microvolt TWA testing was abnormal in six of 22 patients (27%). Holter monitor revealed VT in two patients. Among the clinical variables tested, only LVH was predictive of an abnormal TWA test. The sensitivity, specificity, positive and negative predictive value of LVH for and abnormal TWA test was 100, 56, 46 and 100%. CONCLUSION LVH was common in patients with SCA and disproportional to the number of patients with hypertension. Microvolt TWA tests were abnormal in 27% of patients; however, LVH was the only clinical variable that predicted an abnormal TWA test. Risk stratification of SCA patients may require echocardiographic detection of LVH and an abnormal TWA test due to the high negative predictive value. The significance of an abnormal TWA test should be further evaluated in a large study, with a longer follow-up period.

Biventricular paced QRS predictors of left ventricular lead locations in relation to mortality in cardiac resynchronization therapy.

BACKGROUND Left ventricular (LV) lead location during cardiac resynchronization therapy (CRT) has influenced mortality and heart failure events; however the biventricular paced QRS morphology has not been established as a predictor of LV lead location or mortality. METHODS We evaluated the biventricular paced QRS morphology in 306 patients undergoing CRT in relation to specific anatomic locations. A logistic regression model and Kaplan-Meier survival estimates were used to determine predictors of LV lead location and survival. RESULTS The mean age was 68±13years. Predictors of LV lead location from anterior, lateral, and posterior segments were: absence of R in V1, QS in aVL; and R in aVL, respectively. Absence of an R in II, III, or aVF predicted an inferior site. A QS in V4-V6 differentiated apical from basal sites (p=0.01). LV pacing from sites along the middle cardiac vein revealed a higher mortality (34%), than lateral sites (20%, p=0.02). CONCLUSIONS Biventricular paced QRS criteria were predictive of LV lead locations. The proposed algorithm enhanced the predictive accuracy of these criteria. LV pacing sites along the middle cardiac vein were associated with increased mortality.

Mortality in African-Americans Following Cardiac Resynchronization Therapy: A Single Center Experience

BACKGROUND Cardiac resynchronization therapy (CRT) improves clinical outcomes and reduces mortality in heart failure patients who remain symptomatic despite optimal medical therapy. CRT trials have reported significant hemodynamic benefits, improvement in functional status, and reduced mortality and heart failure hospitalizations. However, African-American patient representation in these studies is limited thus the results may not be applicable to them. We described baseline clinical characteristics of African-American patients undergoing CRT and determined their outcomes relative to those reported in clinical trials. METHODS We evaluated 131 African-American patients with New York Heart Association functional class II-IV heart failure undergoing CRT and determined predictors of all-cause mortality. Kaplan-Meier survival estimates and a Cox proportional hazards model determined mortality and risk of death. RESULTS The mean age was 65 ± 12 years. Over a 6-year period, total mortality in African-Americans was 23% as compared with 29% in the MADIT-CRT trial. Increased mortality was associated with older age (hazard rate (HR) 1.04, 95% confidence interval (CI) 1.01-1.07, P=.01), ischemic cardiomyopathy (HR 2.86, 95% CI 1.36-6.04, P=.006), and absence of treatment with either an angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker (HR 2.75, 95% CI 1.30-5.80, P=.008), or beta-blocker (HR 2.56, 95% CI 0.98-6.69, P=.05). Hydralazine plus nitrate therapy was used in a small number of patients and did not influence mortality outcomes. CONCLUSION African-Americans experience the same survival benefits from CRT as Caucasian patients reported in major clinical trials. Publication indices used to find publications listed in references: PubMed.

Cardiac resynchronization therapy: A comparative analysis of mortality in African Americans and Caucasians

Cardiac resynchronization therapy (CRT) is recommended in patients with heart failure, reduced left ventricular ejection fraction, and a prolonged QRS duration. African Americans are underrepresented in clinical trials and CRT is underutilized; consequently, the benefits and outcomes of CRT are not well‐defined.

Surgical and electrophysiological considerations in the management of a patient with a subcutaneous implantable cardioverter-defibrillator undergoing coronary artery bypass surgery

The use of the implantable cardioverter-defibrillator (ICD) has been the standard of care in the management of patients who have experienced sudden cardiac death and also for those patients at risk for life-threatening ventricular arrhythmias. These transvenous systems carry a substantial risk of periprocedural complications including pneumothorax, cardiac perforation, pericardial effusion or tamponade, hemothorax, venous thrombosis, lead failure or fracture, and infection. In 2010, Bardy et al reported the first successful use of a completely subcutaneous ICD (S-ICD) that is expected to obviate these risks. The U.S. Food and Drug Administration has approved the S-ICD for use in indicated patients without the need for ventricular pacing or cardiac resynchronization therapy. The S-ICD has been effective in the management of at-risk patients; however, its use in surgical patients has been limited. Temporary pacing and sternal wires have interfered with normal S-ICD device function; hence, careful placement of the subcutaneous lead in candidates for cardiac surgery requiring a median sternotomy is of utmost importance. We present the first reported case of a patient with an existing S-ICD system who underwent a median sternotomy for coronary artery bypass graft (CABG) surgery in which removal and repositioning of the S-ICD lead was performed.

Erratum to “Mortality in African-Americans Following Cardiac Resynchronization Therapy: A Single Center Experience” Journal of the National Medical Association 2016:108(1) February 30-39

he publisher regrets the second paragraph of the discussion section was incorrect. The sentence beginning with the word “Fifteen.” should read as follows: T“Fifteen percent of our patients received hydralazine plus nitrates and this may be in-part responsible for the improved survival observed in our study compared to survival reported in the substudy population. However, we did not note any difference in mortality between our patients who received such therapy as opposed to those who didn’t.” Also, Figure 1, Panel B appeared incorrectly. The correct version, with all data included, appears below. The publisher would like to apologize for any inconvenience caused.

Evaluation of patients with complex ventricular arrhythmias: current noninvasive and invasive methods.

Ventricular tachycardia (VT) or ventricular fibrillation is the most frequently documented mechanism of sudden cardiac death (SCD) in patients with coronary heart disease. There is no definitive proof that the abolition of complex ventricular ectopy, accomplished conventionally by pharmacologic therapy, results in the prevention of SCD; in the recent Cardiac Arrhythmia Suppression Trial (CAST), patients treated with encainide or flecainide demonstrated a greater incidence of cardiac death and arrhythmic death than a placebo group. Traditionally, the role of invasive electrophysiologic testing has been reserved for the evaluation of patients with complex ventricular ectopy associated with unexplained syncope, presyncope, or SCD, and for those patients who have sustained VT or ventricular fibrillation. Management of patients with complex ventricular arrhythmias by noninvasive methods (such as the 24-hour ambulatory ECG and exercise testing) has been the approach implemented for most patients thought to be at risk of SCD who have not experienced syncope, presyncope, or sustained VT. The CAST results, coupled with the fact that ambulatory ECG may lack sensitivity and overpredict successful therapy, warrant a discussion of noninvasive and invasive methods currently available for the evaluation and management of patients with complex ventricular arrhythmias. Among some of the relatively new techniques are programmed electrical stimulation and signal-averaged electrocardiography, both of which have been shown to be valuable in delineating high- and low-risk SCD groups.