Bypass surgery versus stenting for the treatment of multivessel disease in patients with unstable angina compared with stable angina.

BACKGROUND: Earlier reports have shown that the outcome of balloon angioplasty or bypass surgery in unstable angina is less favorable than in stable angina. Recent improvements in percutaneous treatment (stent implantation) and bypass surgery (arterial grafts) warrant reevaluation of the relative merits of either technique in treatment of unstable angina. Methods and Results- Seven hundred fifty-five patients with stable angina were randomly assigned to coronary stenting (374) or bypass surgery (381), and 450 patients with unstable angina were randomly assigned to coronary stenting (226) or bypass surgery (224). All patients had multivessel disease considered to be equally treatable by either technique. Freedom from major adverse events, including death, myocardial infarction, and cerebrovascular events, at 1 year was not different in unstable patients (91.2% versus 88.9%) and stable patients (90.4% versus 92.6%) treated, respectively, with coronary stenting or bypass surgery. Freedom from repeat revascularization at 1 year was similar in unstable and stable angina treated with stenting (79.2% versus 78.9%) or bypass surgery (96.3% versus 96%) but was significantly higher in both unstable and stable patients treated with stenting (16.8% versus 16.9%) compared with bypass surgery (3.6% versus 3.5%). Neither the difference in costs between stented or bypassed stable or unstable angina ($2594 versus $3627) nor the cost-effectiveness was significantly different at 1 year. CONCLUSIONS: There was no difference in rates of death, myocardial infarction, and cerebrovascular event at 1 year in patients with unstable angina and multivessel disease treated with either stented angioplasty or bypass surgery compared with patients with stable angina. The rate of repeat revascularization of both unstable and stable angina was significantly higher in patients with stents.

Unexpected ICD pulse generator failure due to electronic circuit damage caused by electrical overstress.

Because it is a lifesaving device, the unexpected failure of an ICD can be catastrophic. We report ICD electronic circuit failure due to electrical overstress damage (EOS) to the high voltage hybird circuit and other electronic components in a series of ICD pulse generator models. Data were obtained from the Multicenter Registry of Pacemaker and ICD Pacemaker and Lead Failures, and from the manufactures' adverse event reports, that were in the FDA's Manufacturer and User Facility Device Experience (MAUDE) database. Of 16 nonbattery Guidant/CPI ICD pulse generator failures reported to the registry, 6 (38%) have been confirmed by the manufacturer to be EOS related, and Guidant/CPI has reported 273 such failures to the FDA as of 12/29/00. The signs of failure included loss of telemetry and inability to deliver therapy, and some patients have experienced serious adverse events. Hybrid circuit damage may have occurred during capacitor charging or reform, and the majority appears to have happened during normal ICD function. While the incidence of this problem is unknown, a management strategy should be adopted that includes routine follow-up every 3 months and device evaluation after a shock or exposure to external defibrillation or electrosurgical devices. This study suggests that additional data are needed to determine the incidence of this problem, and that our present methods for monitoring the performance of ICD's following market release are inadequate.

Guidelines for pacemaker follow-up in Canada: a consensus statement of the Canadian Working Group on Cardiac Pacing.

A survey on Canadian pacing practices conducted in 1997 revealed a widespread desire for national guidelines on pacemaker follow-up. The present guidelines for pacemaker follow-up are a consensus statement of the Canadian Working Group on Cardiac Pacing. Direct patient follow-up rather than transtelephonic monitoring is desirable. Patients should be assessed at a minimum of within 72 h of implantation, at two to 12 weeks and at six months following implantation, and annually thereafter. More frequent assessments may be required for some patients. This depends on associated cardiovascular problems and specific devices. A typical follow-up visit should include a targeted cardiovascular assessment, interrogation of the pacing system, review of telemetered data, assessment of the underlying rhythm, assessment of pacing and sensing thresholds, and appropriate reprogramming of pacing parameters to optimize device function and longevity.

Reliability of coated wire defibrillation leads.

A higher rate of complications and need for reoperation has been identified with epicardial and endocardial defibrillator systems. Improved reliability may be achieved with alternate designs that use coated wire and coated coil conductors. Six-year reliability in the 98% range is reported for one bipolar design, the Sulzer Intermedics Intervene lead.

Clinical experience with passive-fixation coradial bipolar endocardial pacing leads. ThinLine Clinical Investigators.

Bipolar, transvenous, passive-fixation leads (ThinLine, Sulzer Intermedics Inc., Angleton, TX, USA) incorporating coradial individually coated conductor coils, and a redundant external 55D polyurethane insulation sheath were developed. The diameter of the new leads (< 5 Fr) is in the range of available unipolar leads and is considerably smaller than conventional bipolar pacing leads. From January 9, 1994 to November 12, 1996, 1,536 model 432-04 (523 atrial) and 430-10 (1,013 ventricular) leads were implanted in 1,068 patients at 50 US and 5 Canadian centers to evaluate their safety and efficacy. The study included a general phase, with follow-ups at 1, 3, 6, 12, 18, and 24 months; and a randomized intensive phase with collection of more data and additional 2- and 6-week follow-ups. Capture and sensing thresholds, lead impedance, and handling characteristics were evaluated. Clinical events were monitored and performance was compared to that of two commercially available conventional (coaxial) leads: Sulzer Intermedics models 432-03 (atrial) and 430-07 (ventricular). During a total of 17,530 device months, there were two lead failures, no lead related deaths, 32 explants, 37 complications, and no unexpected adverse device effects. Capture thresholds were lower than those for coaxial controls with identical electrodes, sensing was comparable, lead impedances were within clinically acceptable ranges, and investigators found overall handling characteristics good to excellent. ThinLine coradial bipolar leads are safe and effective for cardiac pacing and sensing.

Cardiac pacing in Canada in 1998: working towards optimal pacing therapy. Canadian Working Group on Cardiac Pacing.

The Canadian Working Group on Cardiac Pacing (CWGCP) was formed in 1996 with the primary goal of promoting optimal pacing therapy in Canada. In 1997, the CWGCP conducted a survey of pacing practices across Canada. Ninety-two of 125 implanting programs (74%) responded. Implant rates vary by province--from 39 per 100,00 population in Ontario to 63 per 100,000 population in Nova Scotia and Prince Edward Island. Variations in regional implant rates persist even after correcting for the age of the population. Physiological pacing was used for 35% of all implants in Canada in 1996/97. There were marked differences across Canada in the mode of pacing selected. In western Canada, 39.5% of pacing systems implanted were physiological compared with 18.2% in Atlantic Canada and 29% in Quebec. There were also differences in follow-up practices. Approximately 40% of centres follow patients with single chamber pacemakers annually, whereas most other centres still follow these patients every six months. Economic constraints, the size of pacing programs and the involvement of committed pacing physicians are factors that may influence the regional differences in cardiac pacing across Canada.

Multiple mechanical valve replacement surgery comparison of St. Jude Medical and CarboMedics prostheses.

OBJECTIVE: The experience with the St. Jude Medical (SJM) and CarboMedics (CM) bileaflet mechanical prostheses was evaluated to determine thromboembolic and hemorrhagic complications and predictive risk factors. METHODS: From 1989 to 1994, a total of 246 patients had multiple valve replacement (SJM, 140; CM, 106); concomitant procedures 20.3% (50) [coronary artery bypass 10.6% (26)] and 53.7% (132) previous cardiac surgery, primarily valve replacement procedures. The pre-operative variables [coronary artery disease, previous cardiovascular surgery, concomitant procedures, valve lesion (except mitral stenosis), status, atrial fibrillation, and NYHA III/IV] did not distinguish the prosthesis-type (pNS). RESULTS: The prosthesis-type and the pre-operative variables, including atrial fibrillation, were not predictive of overall thromboembolism (TE). The linearized rate of total TE events for overall multiple replacements (MR) was 5.4%/patient-year (minor, 2.52; major 2.85); the total TE for CM and SJM was 5.4%/patient-year, respectively. The < or = 30 day major TE crude rate was 0.82%, while the > 30 day major event rate was 2.7%/patient-year. Of the total (major and minor) TE events 100% (3) of < or = 30 days and 72% (29), > 30 days had an INR < 2.5 at or immediately prior to the event. The thrombosis rate (included in total TE events) was 0.67%/patient-year (4 events, 100% INR < 2.5). Of the various TE event categories the prosthesis-types (CM and SJM) were not differentiated (pNS). The freedom, at 5 years, from major/fatal TE, thrombosis and hemorrhage from anticoagulation was 89.3 +/- 3.8% for CM and 87.9 +/- 3.7% for SJM and, 91.3 +/- 3.5% and 89.3 +/- 3.7%, respectively, (pNS) exclusive of early events. CONCLUSIONS: The performance of the CarboMedics and St. Jude Medical prostheses in multiple valve replacement surgery in this non-randomized prospective study revealed no significant differences in performance with regard to thromboembolic and hemorrhagic complications.

Bileaflet mechanical prostheses in mitral and multiple valve replacement surgery: influence of anticoagulant management on performance.

BACKGROUND: The St. Jude Medical (SJM) mechanical prosthesis has been the predominant mechanical prosthesis worldwide since its introduction in 1977. The CarboMedics (CM) mechanical prosthesis, also a bileaflet pyrolite carbon prosthesis, was introduced in 1986 and was approved by the Food and Drug Administration of the United States in 1993. The experience of the two prostheses was evaluated in a parallel, nonrandomized study commencing with the CM investigational study in 1989. METHODS AND RESULTS: The clinical performance of the two prostheses was evaluated in accordance with the Guidelines for Reporting Morbidity and Mortality After Cardiac Valvular Operations. The CM prosthesis was implanted in 239 mitral valve replacements (MVR) and 106 multiple valve replacements (MR), and the SJM prosthesis was implanted in 379 MVR and 137 MR. The CM and SJM populations were not distinguished within MVR and MR for mean age, previous surgery, concomitant surgery, mean follow-up, and late mortality (P=NS). The linearized occurrence rate for the combined experience for major thromboembolic and hemorrhage events >30 days was 3.4% of patients per year for MVR (inclusive of cerebral thromboembolism reversible, major; systemic; thrombosis; and fatal; and major systemic hemorrhage) and for MR was 3.9% of patients per year (P=NS between prostheses by position). The major crude event rate for < or =30 days was 1.3% for MVR and 1.2% for MR (P=NS between prostheses by position). The inadequacy of anticoagulation (as determined by international normalized ratio 2.5) for all thromboembolic events (major and minor) < or =30 days was 93%, and that for >30 days was 75%. The freedom from major thromboembolism for MVR at 3 years was 92.7+/-1.9% for CM and 94.0+/-1.5% for SJM; for MR, it was 94.2+/-3.0% for CM and 93.5+/-2.5% for SJM (P=NS). The freedom from major thromboembolism exclusive of early events for MVR at 3 years was 94.4+/-1.8% for CM and 94.8+/-1.4% for SJM, and for MR, it was 94.2+/-3.0% for CM and 95.0+/-2.2% for SJM (P=NS). The freedom from major thromboembolism and hemorrhage for prostheses (CM and SJM) by valve positions (MVR and MR) was also indistinguishable (P=NS). CONCLUSIONS: There are no distinguishing performance characteristics with regard to thromboembolic and hemorrhagic events between the CM and the SJM mechanical prostheses in MVR and MR. There was an identified need for improvement in the early and late anticoagulant management. A randomized trial with optimization of anticoagulant management between the CM and SJM mechanical prostheses is recommended.

Primary cardiac tumors: forty years' experience with 71 patients.

BACKGROUND: Primary cardiac tumors are infrequent, and few cardiac surgeons have extensive experience in treating them. The majority of the tumors are benign. As noninvasive diagnostic imaging of cardiac masses continues to improve, the number of these tumors that are seen by clinicians will increase. More of the malignant tumors may be curable if detected at an earlier stage. METHODS: A retrospective review was conducted of all patients with primary cardiac tumors managed by a university teaching center over a period of 40 years, using hospital medical records and a Provincial cardiovascular surgery database. RESULTS: Seventy-one patients (25 males and 46 females) with primary cardiac tumors were identified. Fifty-seven (80%) were benign masses and 14 (20%) were malignant masses. Twenty-eight percent of the tumors in men were malignant (7 of 25) compared with only 15% in women (7 of 46). Seventy-two percent of the masses were located in the left atrium. Forty-three percent of tumors in the right atrium were malignant (6 of 14) compared with only 14% in the left atrium (7 of 51). Complete resection was possible for 50 of 52 benign atrial tumors (96%) but for only 5 of 14 malignant tumors (36%). There was one perioperative death (1.4%). Three patients had no surgery because of their poor medical condition. Two of the patients with unresectable malignant tumors were still alive at last follow-up. The remaining 12 patients with malignancy have all died of their disease. CONCLUSIONS: Primary cardiac tumors are uncommon. Most patients present with symptoms of congestive heart failure. The second most common presenting symptom is embolization. Improvement in noninvasive diagnostic technology has increased the number of patients identified with a primary cardiac tumor and has also increased the number referred for surgical resection. The majority of left atrial tumors were benign, whereas up to one-half of tumors found in the right atrium were malignant. A greater proportion of malignant primary tumors were found in men than in women. Malignant cardiac tumors tend to be diagnosed after they have become extensive and the patients already have a very grave prognosis.

Bipolar leads for use with permanently implantable cardiac pacing systems: a review of limitations of traditional and coaxial configurations and the development and testing of new conductor, insulation, and electrode designs.

The unacceptable rate of mechanical failures, threshold problems, and recalls experienced with many coaxial bipolar cardiac pacing lead designs are reviewed in detail. To address these problems, redundant insulation coradial atrial and ventricular tined leads (AL and VL, respectively) with iridium oxide electrodes were developed and subjected to extensive accelerated testing. There were no mechanical failures. The new lead body design proved to be much more durable than widely used trifilar MP35N configurations. The data reviewed and early and current test results are strongly supportive of tightly coupled insulation being a major factor in improving lead durability as long as the insulating material is not stressed. In addition to improving flex life, insulation adherence to the conductor may reduce the potential for ionic degradation. Pacing and sensing thresholds in animal studies of the new leads were within the reported range for leads with steroid eluting electrodes. A multicenter Canadian clinical trial was initiated with the first implant in early January 1994. By November 1995, 110 VL and 82 AL had been placed in 124 patients and followed for a mean of 11 +/- 6 months; maximum 21, total 1355. There were 60 males and 64 females with a mean age of 64 +/- 16 years, range 15-88. Primary indications for pacing were AV block in 61 patients, sick sinus syndrome in 53, vasovagal syncope in 4, and congestive heart failure in 7. Many patients had associated or primary tachyarrhythmias, including 111 with supraventricular and 12 with ventricular. Forty-two percent of patients (52/124) had prior cardiac procedures, including 18 open heart surgeries and 20 AV nodal ablations. At implant, 8 lead characteristics were rated good or excellent in 90% (746/829) of evaluations. X-ray visibility was of concern in 10% of patients (12/124). Three perioperative complications occurred, including displacement of one AL (1.2%) and one VL (0.9%). There were no subsequent mechanical (connector, conductor, or insulation) or functional (exit block, micro or macro displacement, or over- or undersensing) problems. Implant pacing thresholds (PT) at 0.45 ms were AL, 0.6 +/- 0.2 (74) and VL 0.4 +/- 0.2 V; impedance (Z) at 3.5 V output AL 373 +/- 77 (82) and VL 497 +/- 117 omega. Sensing thresholds (ST) were AL 3.1 +/- 1.6 (74) and VL 10.3 +/- 4.9 mV. Ventricular lead data were obtained for all patients (N = 110). Atrial lead data are incomplete, because some patients were in atrial fibrillation during implantation. After 12 months, AL PT at 1.5 V output was 0.18 +/- 0.10 ms (21) and at 2.5 V was 0.10 +/- 0.053 (22). Associated AL ST was 3.3 +/- 0.9 mV (21) AL Z 500 +/- 65 omega (25). After 18 months VL PT at 1.5 V was 0.15 +/- 0.10 ms (9) and at 2.5 V output was 0.09 +/- 0.04 ms (9). Associated VL ST was > 7.5 +/- 2.4 mV (9) and VL Z 497 +/- 105 omega (9). Follow-up time discrepancy is due to the VL being available 6 months earlier than the AL. There were no 30-day deaths and only one late death at 10 months in a patient with chronic atrial fibrillation. Death was unrelated to pacer or lead function. At 1 year, 68% AL (15/22) and 62% (24/39) captured at 0.5 V and < or = 1 ms pulse width output. Innovative adherent insulation coradial bipolar lead conductors of the design studied combined with coated iridium oxide electrodes provide for a negligible incidence of mechanical or functional failure with clinical follow-up now approaching 3 years. Excellent acute and chronic sensing and pacing thresholds have been documented. Late thresholds have continued to improve gradually. Long-term clinical pacing at < or = 1.5 V output with a large safety margin is feasible in essentially all patients. This coradial design produces very flexible < 5 French bipolar redundantly insulated lead bodies allowing both AL and VL to simultaneously pass through a single 10 French introducer sheath. (ABSTRACT TRUNCATED)

Reliability audit of a regional cardiac surgery registry.

OBJECTIVE: The British Columbia Provincial Cardiac Registry collects demographic and clinical data on all patients who undergo cardiac surgery procedures in the province. The purpose of this study was to compare the reliability of data contained in Registry with data contained in hospital charts. METHODS: Registry and hospital charts were compared for 480 cases. Thirty cases were randomly selected for the province's 16 cardiac surgeons. For each case, 10 distinct fields were selected for analysis and classified as consistent, inconsistent, or rejected (data unavailable in one or other source). RESULTS: The overall rate of consistency between charts and the Registry was 86.4%, with an inconsistency rate of 9.9% and a rejection rate of 3.7%. Consistency rates varied significantly across the 10 fields and among the 16 surgeons. Pairwise comparisons of rates between fields indicated that specific field types were problematic and should be targeted for improvement. In addition, pairwise comparisons of rates between surgeons indicated that further education on Registry use is required. CONCLUSIONS: Recommendations for database design and management include provision of standard definitions for all fields; education of users; extension of the number of mandatory fields; revision of check-off box fields to yes/no/unsure fields; and collection of data close to the time that it is generated.

Unilateral versus bilateral internal mammary revascularization. Survival and event-free performance.

BACKGROUND: The influence of unilateral (UL) and bilateral (BL) mammary artery revascularization, within age groups < or = 60 years and > 60 years, on patient survival, ischemic-related events, and interventional management was studied in 1142 patients who had coronary artery bypass graft surgery between 1984 and 1992. METHODS AND RESULTS: UL revascularization was performed in 765 (67%) and BL in 377 (33%) patients with supplemental vein grafts. The overall early and hospital mortality rate was 2.7%. For UL in the age group < or = 60 years, it was 1.1%; for BL < or = 60 years, 1.3% (P = NS); for UL > 60 years, 4.3%; and for BL > 60 years, 2.8% (P = NS). Twenty-five preoperative patient characteristics representing demographics, extent of disease, concomitant disease, ventricular dysfunction, previous surgery, and status did not differentiate the patient groups (P = NS). Patient survival at 5 years was not different: 94% for UL < or = 60 years, 95% for BL < or = 60 years, 91% for UL > 60 years, and 86% for BL > 60 years (P = NS). The freedom from ischemic-related events was not different at 5 years (P = NS). The freedom from recurrent angina was 78% for UL < or = 60 years, 88% for BL < or = 60 years, 82% for UL > 60 years, and 83% for BL > 60 years (P = NS). The myocardial infarction freedom was 98% for UL < or = 60 years, 96% for BL < or = 60 years, 99% for UL > 60 years, and 97% for BL > 60 years (P = NS). The freedom from sudden unexpected death and cardiac death did not differentiate the groups (P = NS). The freedom from angioplasty and reoperation did not differentiate the groups (P = NS). The freedom from all ischemic-related and interventional events was 76% for UL < or = 60 years, 84% for BL < or = 60 years, 81% for UL > 60 years, and 79% for BL > 60 years (P = NS). A trend exists for less angina pectoris in the bilateral population < or = 60 years, which reflects in the trend in the freedom from overall events. CONCLUSIONS: UL and BL mammary artery revascularizations have the same early mortality regardless of age but do not reveal any advantage for BL revascularization at 5 to 7 years.