Robert C. Canby

Bio: Robert C. Canby is an academic researcher from Johns Hopkins University. The author has contributed to research in topics: Medicine & Heart failure. The author has an hindex of 5, co-authored 5 publications receiving 1955 citations.

Combined cardiac resynchronization and implantable cardioversion defibrillation in advanced chronic heart failure: the MIRACLE ICD Trial.

Abstract: ContextCardiac resynchronization therapy (CRT) through biventricular pacing is an effective treatment for heart failure (HF) with a wide QRS; however, the outcomes of patients requiring CRT and implantable cardioverter defibrillator (ICD) therapy are unknown.ObjectiveTo examine the efficacy and safety of combined CRT and ICD therapy in patients with New York Heart Association (NYHA) class III or IV congestive HF despite appropriate medical management.Design, Setting, and ParticipantsRandomized, double-blind, parallel-controlled trial conducted from October 1, 1999, to August 31, 2001, of 369 patients with left ventricular ejection fraction of 35% or less, QRS duration of 130 ms, at high risk of life-threatening ventricular arrhythmias, and in NYHA class III (n = 328) or IV (n = 41) despite optimized medical treatment.InterventionsOf 369 randomized patients who received devices with combined CRT and ICD capabilities, 182 were controls (ICD activated, CRT off) and 187 were in the CRT group (ICD activated, CRT on).Main Outcome MeasuresThe primary double-blind study end points were changes between baseline and 6 months in quality of life, functional class, and distance covered during a 6-minute walk. Additional outcome measures included changes in exercise capacity, plasma neurohormones, left ventricular function, and overall HF status. Survival, incidence of ventricular arrhythmias, and rates of hospitalization were also compared.ResultsAt 6 months, patients assigned to CRT had a greater improvement in median (95% confidence interval) quality of life score (–17.5 [–21 to –14] vs –11.0 [–16 to –7], P = .02) and functional class (–1 [–1 to –1] vs 0 [–1 to 0], P = .007) than controls but were no different in the change in distance walked in 6 minutes (55 m [44-79] vs 53 m [43-75], P = .36). Peak oxygen consumption increased by 1.1 mL/kg per minute (0.7-1.6) in the CRT group vs 0.1 mL/kg per minute (–0.1 to 0.8) in controls (P = .04), although treadmill exercise duration increased by 56 seconds (30-79) in the CRT group and decreased by 11 seconds (–55 to 12) in controls (P<.001). No significant differences were observed in changes in left ventricular size or function, overall HF status, survival, and rates of hospitalization. No proarrhythmia was observed and arrhythmia termination capabilities were not impaired.ConclusionsCardiac resynchronization improved quality of life, functional status, and exercise capacity in patients with moderate to severe HF, a wide QRS interval, and life-threatening arrhythmias. These improvements occurred in the context of underlying appropriate medical management without proarrhythmia or compromised ICD function.

Intrathoracic Impedance vs Daily Weight Monitoring for Predicting Worsening Heart Failure Events: Results of the Fluid Accumulation Status Trial (FAST)

Abstract: The relative sensitivity and unexplained detection rate of changes in intrathoracic impedance has not been compared with standard heart failure (HF) monitoring using daily weight changes. The Fluid Accumulation Status Trial (FAST) prospectively followed 156 HF patients with implanted cardioverter-defibrillator or cardiac resynchronization therapy defibrillator devices modified to record daily changes in intrathoracic impedance in a blinded fashion for 537±312 days. Daily impedance changes were used to calculate a fluid index that could be compared with a prespecified threshold. True positives were defined as adjudicated episodes of worsening HF occurring within 30 days of a fluid index above threshold or an acute weight gain. Unexplained detections were defined as threshold crossings or acute weight gains not associated with worsening HF. Impedance measurements were performed on >99% of follow-up days, compared with only 76% of days for weight measurements. Sixty-five HF events occurred during follow-up (0.32/patient-year). Forty HF events were detected by impedance but not weight, whereas 5 were detected by weight but not impedance. Sensitivity was greater (76% vs 23%; P<.0001) and unexplained detection rate was lower (1.9 vs 4.3/patient-year; P<.0001) for intrathoracic impedance monitoring at the threshold of 60Ω days compared with acute weight increases of 3 lbs in 1 day or 5 lbs in 3 days and also over a wide range of fluid index and weight thresholds. The sensitivity and unexplained detection rate of intrathoracic impedance monitoring was superior to that seen for acute weight changes. Intrathoracic impedance monitoring represents a useful adjunctive clinical tool for managing HF in patients with implanted devices.

Results of catheter ablation of typical atrial flutter.

Abstract: The purpose of this study was to evaluate the safety and efficacy of radiofrequency (RF) ablation of typical atrial flutter by using an 8-mm electrode catheter and a 100-W RF power generator A limitation of previous trials of catheter ablation of atrial flutter is that the data were not collected as part of a prospective multicenter clinical trial The study results associated catheter ablation of typical atrial flutter in a cohort of 150 patients with an 88% acute efficacy rate At 6-month follow-up, recurrent typical atrial flutter was observed in 13% of patients Of the 12 patients with typical atrial flutter recurrence, 4 were symptomatic and 8 were asymptomatic Procedure duration was a significant predictor of typical atrial flutter recurrence The 12-month rate for development of atrial fibrillation was 30% Catheter ablation of atrial flutter was associated with significant improvements in 5 of 8 domains of the Short Form 36 Survey (quality of life) and significant decreases in 13 of the 16 symptoms of the Symptom Checklist The device- or procedure-related complication rate was 27% Skin burns occurred at the dispersive pad site due to stronger RF power in 3 patients Use of a dual dispersive pad system mitigated this problem Thus, the results of this study associated catheter ablation of atrial flutter with high acute efficacy, a small risk of recurrent atrial flutter, and an important risk of atrial fibrillation during follow-up

The effect of cardiac resynchronization on morbidity and mortality in heart failure

Abstract: background Cardiac resynchronization reduces symptoms and improves left ventricular function in many patients with heart failure due to left ventricular systolic dysfunction and cardiac dyssynchrony We evaluated its effects on morbidity and mortality methods Patients with New York Heart Association class III or IV heart failure due to left ventricular systolic dysfunction and cardiac dyssynchrony who were receiving standard pharmacologic therapy were randomly assigned to receive medical therapy alone or with cardiac resynchronization The primary end point was the time to death from any cause or an unplanned hospitalization for a major cardiovascular event The principal secondary end point was death from any cause results A total of 813 patients were enrolled and followed for a mean of 294 months The primary end point was reached by 159 patients in the cardiac-resynchronization group, as compared with 224 patients in the medical-therapy group (39 percent vs 55 percent; hazard ratio, 063; 95 percent confidence interval, 051 to 077; P<0001) There were 82 deaths in the cardiac-resynchronization group, as compared with 120 in the medical-therapy group (20 percent vs 30 percent; hazard ratio 064; 95 percent confidence interval, 048 to 085; P<0002) As compared with medical therapy, cardiac resynchronization reduced the interventricular mechanical delay, the end-systolic volume index, and the area of the mitral regurgitant jet; increased the left ventricular ejection fraction; and improved symptoms and the quality of life (P<001 for all comparisons) conclusions In patients with heart failure and cardiac dyssynchrony, cardiac resynchronization improves symptoms and the quality of life and reduces complications and the risk of death These benefits are in addition to those afforded by standard pharmacologic therapy The implantation of a cardiac-resynchronization device should routinely be considered in such patients

ACC/AHA 2005 Guideline Update for the Diagnosis and Management of Chronic Heart Failure in the Adult

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2009 Focused Update Incorporated Into the ACC/AHA 2005 Guidelines for the Diagnosis and Management of Heart Failure in Adults A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines: Developed in Collaboration With the International Society for Heart and Lung Transplantation

Abstract: Mariell Jessup, MD, FACC, FAHA, Chair [*][1] William T. Abraham, MD, FACC, FAHA[†][2] Donald E. Casey, MD, MPH, MBA[‡][3] Arthur M. Feldman, MD, PhD, FACC, FAHA[§][4] Gary S. Francis, MD, FACC, FAHA[§][4] Theodore G. Ganiats, MD[∥][5] Marvin A. Konstam, MD, FACC[¶][6] Donna M.