The implantable cardioverter-defibrillator: postcode prescribing in the UK 1998-2002.

OBJECTIVE: To determine the rate of implantable cardioverter-defibrillator (ICD) implantation across the UK during the period 1998 to 2002. DESIGN: Observational self reporting with cross checking. SETTING: All ICD implanting centres coordinated by the National Pacemaker and ICD Database. PATIENTS: Every patient receiving an ICD in the UK from 1998 to 2002. MAIN OUTCOME MEASURES: Date of implantation and postcode of each ICD recipient during the study period. RESULTS: ICD implantation increased in the UK in the five year period studied but fell far short of the European average and national targets. Implantation rates varied greatly by region. CONCLUSIONS: The low rate of ICD implantation in the UK and the disparity between regions require further study to determine the barriers to this evidence based treatment.

Improving care for patients with acute coronary syndromes: initial results from the National Audit of Myocardial Infarction Project (MINAP).

OBJECTIVE: To describe the improvements in care that have followed the introduction of an electronic data entry and analysis system providing contemporary feedback on the management of acute coronary syndromes in 230 hospitals in England and Wales. DESIGN: Observational study METHODS: A secure electronic system was used to transfer encrypted data on patients with acute coronary syndromes from collaborating hospitals to central servers for analysis. Immediate online data entry to the central servers by hospitals allowed contemporary analyses of performance and immediate comparison with the national aggregate performance. RESULTS: The records of 156 902 patients receiving a final diagnosis of acute coronary syndrome during three years between October 2000 and September 2003 were analysed. Of 69 113 patients with ST segment elevation infarction, 75.4% received thrombolytic treatment. Between the first and last years of the study the median interval from hospital arrival to treatment fell for eligible patients from 38 (interquartile range 22-58) to 20 (interquartile range 14-28) minutes. By mid 2003 77.6% were receiving thrombolytic treatment within 30 minutes of arrival. The proportion treated within two hours of onset of symptoms increased from 32.5% to 40.3% (a difference of 7.8 percentage points, p < 0.0001). The use of secondary prevention medication for acute coronary syndromes increased over this period: angiotensin converting enzyme inhibitors, 62.4% to 72.4%; beta blockers, 76.3% to 82.6%; statins, 69.6% to 83.8%; and aspirin, 89.3% to 90.2%. CONCLUSION: The provision of contemporary online performance analyses has underpinned substantial improvement in the care of patients with acute coronary syndromes.

The World Survey of Cardiac Pacing and Implantable Cardioverter Defibrillators: calendar year 1997--Europe.

The registry of the European Working Group on Cardiac Pacing (EWGCP) is based on the European Pacemaker Identification Card originally designed in July 1978. National registration centers collect the local data and send aggregated annual data to the EWGCP. For 1997, data were obtained from 2,887 hospitals in 20 European countries representing a population of 568 million. Across all participating countries, the median value for all implanted pacemakers was 378 per million population. For initial pacemaker implants, the median value was 290 per million population. Single chamber atrial pacing was important in Denmark, the Netherlands, Poland, Slovak Republic, Spain, and Sweden for the treatment of sick sinus syndrome. Dual chamber pacing accounted for < 50% of initial implants in only 5 of 14 countries for atrioventricular block, and in only 3 of 15 countries for sick sinus syndrome. In 7 of 15 countries, unipolar ventricular leads were used in > or = 50% of cases. In 6 of 14 countries, there was > 15% use of unipolar atrial leads. Nine of 13 countries frequently used atrial active-fixation leads. For the 1997 survey, ICD data were obtained from 16 countries. The total number of ICDs per million population was a median value of 14. Initial ICD implants per million population was 11. Only 3 of 16 countries implanted a total of 30 or more ICDs per million population. Pacing and ICD practices were dependent on the availability of medical and technical resources and influenced by economic constraints inherent in health care administration and insurance coverage patterns.

Difference in the mortality of the CABRI diabetic and nondiabetic populations and its relation to coronary artery disease and the revascularization mode.

In diabetics with coronary artery disease (CAD), there remains uncertainty as to whether revascularization by percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass surgery (CABG) is preferable. To address this, 4-year mortality and level of pre- and postrevascularization angiographic CAD (measured by a series of coronary scores) were compared between both diabetics and nondiabetics and between revascularization modes in the Coronary Angioplasty versus Bypass Revascularization Investigation population as a whole, and then substratified by diabetic status and then by procedure to which they were randomized. The 1,054 randomized subjects contained 125 diabetics (11.9%) who had significantly greater mortality than nondiabetics (RR 2.19, p = 0.001). Among diabetics or nondiabetics, there was no significant mortality difference between those randomized to PTCA versus those to CABG. Diabetics randomized to PTCA and those to CABG had higher mortalities than respective nondiabetics; the association reached significance only in the former (RR 2.41, p = 0.002). All subgroups had similar prerevascularization CAD. Postrevascularization residual CAD was consistently significantly greater in PTCA than in respective CABG subgroups. Most measurements of CAD were greater in diabetic than in nondiabetic subgroups, but none was significant. In the Coronary Angioplasty versus Bypass Revascularization Investigation, diabetics had double the mortality of nondiabetics; this difference was statistically significant both for the entire population and for those randomized to PTCA, but not for those randomized to CABG. Among diabetics or nondiabetics, there was no significant mortality difference between PTCA and CABG. The higher diabetic mortality was more likely related to more rapid disease progression than to greater postrevascularization disease.

The effect of adjusting for baseline risk factors and post revascularisation coronary disease on comparisons between coronary angioplasty and bypass surgery.

BACKGROUND: In CABRI at 1 year PTCA was associated with greater repeat revascularisation and angina (but not myocardial infarction or death). We determined whether adjusting for baseline risk factors and post revascularisation coronary disease offsets this disadvantage of PTCA. METHODS: In the CABRI population the crude association of revascularisation mode (i.e. PTCA or CABG) with four clinical outcome (i.e. mortality, myocardial infarction, repeat revascularisation and angina) was adjusted for the baseline risk factors using a logistic regression model for each clinical outcome. A number of measures of angiographic coronary disease were used to assess post revascularisation coronary disease. One at a time, each of these measures was added to each of the four outcome models, to adjust for post revascularisation coronary disease. RESULTS: Comparing adjusted and crude unadjusted association of PTCA with repeat revascularisation there was an increase from 12.8 (P<0.0005) (crude relative risk) to 16.7 (P<0.0005) (adjusted odds ratio), with angina, from 1.89 (P=0.001) to 1.98 (P<0.0019), and with mortality from 1.84 (P=0.092) to 2.15 (P=0.060). PTCA was not significantly associated with myocardial infarction, either crudely or after adjustment. CONCLUSION: Adjusting for baseline risk factors and post revascularisation coronary disease tended to strengthen rather than weaken associations between PTCA and 1 year mortality, repeat revascularisation and angina at 1 year.

Relation between coronary artery disease, baseline clinical variables, revascularization mode, and mortality. CABRI Participants. Coronary Angioplasty vs. Bypass Revascularisation Investigation.

The Coronary Angioplasty vs. Bypass Revascularisation Investigation (CABRI) trial comparing percutaneous transluminal coronary angioplasty (PTCA) with coronary artery bypass grafting did not show a difference in mortality with either procedure. Nonrandomized studies suggest that coronary artery disease (CAD) severity and distribution influences outcome. In the present study we explored the effect of prerevascularization CAD on 1-year mortality in the CABRI population, while adjusting for other baseline variables. Of the 1,054 patients recruited, there were sufficient angiographic results to derive the CAD scores in 974 (92.4%). Of these 974, there were 32 deaths. A number of CAD scores, both weighted for proximal disease (Duke and Leaman) and nonweighted, were used. These scores were then cross-tabulated against mortality. Demographic and clinical variables were also cross-tabulated against mortality and used to derive an initial logistic regression model to predict mortality. The effect of adding each of the CAD scores to this initial model was then assessed. After inclusion of the CAD scores, the best model was: (1) presence of peripheral vascular disease (odds ratio [OR] 3.89, p = 0.0025), (2) previous cerebrovascular accident (OR 2.86, p = 0.043), (3) older age (OR 1.05, p = 0.039), (4) a higher Duke score (OR 2.84, p = 0.0061), and (5) having undergone PTCA (OR 2.12, p = 0.047). In the CABRI population, adjustment for baseline variables, including prerevascularization CAD, revealed significantly higher mortality in those who underwent PTCA than in those who underwent coronary artery bypass grafting.

Trials of angioplasty and surgery: CABRI.

The medium term (4-year post randomization) results from CABRI indicate that the principal difference between those randomized to coronary angioplasty and those to coronary surgery has been the much greater need for repeat revascularization in the former. A number of factors may play a role in the greater repeat revascularization rate post coronary angioplasty, these include coronary restenosis, residual coronary artery disease, coronary artery disease progression. In the longer term, graft failure in those who have undergone coronary surgery will be important, and it remains to be seen what the effect of this will be.

Impact of postangioplasty restenosis on comparisons of outcome between angioplasty and bypass grafting. Coronary Angioplasty versus Bypass Revascularisation Investigation (CABRI) Investigators.

Restenosis is a major limitation of percutaneous transluminal coronary angioplasty (PTCA). In this study, we assessed the impact of restenosis on PTCA with reference to coronary angioplasty bypass grafting (CABG). In the Coronary Angioplasty versus Bypass Revascularisation Investigation (CABRI) PTCA population, those who had restenosis were defined as those needing a second revascularization at a site revascularized at the initial procedure. The 1-year clinical outcome of the nonrestenotic group (n=437) was compared with those who underwent CABG (n=453). There was no difference in deaths. In the nonrestenotic PTCA group, the incidence of more infarctions was insignificant (relative risk [RR] 1.9, 95% confidence intervals [CI] 0.96 to 3.75, p=0.064), there was a much greater need for repeat revascularization (RR 8.6, CI 5.14 to 14.41, p <0.0005), and patients had a poorer angina status (RR 1.46, CI 1.01 to 2.13, p=0.046). Using 2 measures of coronary disease, the degree of pre- and postrevascularization disease was compared between groups. There were no differences in prerevascularization disease. However, using either measure, residual postrevascularization disease was more frequent in the nonrestenotic PTCA group. Restenosis only partially accounts for the greater morbidity seen after PTCA, compared with CABG, in multivessel disease. The greater likelihood of residual disease post-PTCA may contribute to this greater morbidity.

Differential restenosis rate of individual coronary artery sites after multivessel angioplasty: implications for revascularization strategy. CABRI Investigators. Coronary Angioplasty versus Bypass Revascularisation Investigation.

BACKGROUND: Restenosis is a major limitation of angioplasty. In this analysis we assessed the effects of lesion site and quality of dilatation on restenosis rate in the Coronary Angioplasty versus Bypass Revascularization Investigation population who underwent angioplasty. METHODS: The angiographic quality of the successful angioplasty revascularization at each site was assessed, and the subsequent restenosis rate was determined. Restenosis was defined by the need for a second angioplasty at the initial site or by surgical coronary bypass grafting at or distal to the initial site. RESULTS: The restenosis rate was unaffected by quality of dilatation but was significantly more common in the proximal left anterior descending artery compared with other sites, whether or not optimal dilatation had been achieved (relative risk 2.0 and 1.9, respectively). CONCLUSION: Revascularization strategies in multivessel disease should consider the presence or absence of a proximal left anterior descending artery target. Furthermore in studies in which restenosis is an outcome of interest, an allowance should be made for the distribution of target disease.

An implantable intracardiac accelerometer for monitoring myocardial contractility. The Multicenter PEA Study Group.

As the myocardium contracts isometrically, it generates vibrations that are transmitted throughout the heart. These vibrations can be measured with an implantable microaccelerometer located inside the tip of an otherwise conventional unipolar pacing lead. These vibrations are, in their audible component, responsible for the first heart sound. The aim of this study was to evaluate, in man, the clinical feasibility and reliability of intracavity sampling of Peak Endocardial Acceleration (PEA) of the first heart sound vibrations using an implantable tip mounted accelerometer. We used a unidirectional accelerometer located inside the stimulating tip of a standard unipolar pacing lead: the sensor has a frequency response of DC to 1 kHz and a sensitivity of 5 mV/G (G = 9.81 m/s-2). The lead was connected to an external signal amplifier with a frequency range of 0.05-1,000 Hz and to a peak-to-peak detector synchronized with the endocardial R wave scanning the isovolumetric contraction phase. Following standard electrophysiological studies, sensor equipped leads were temporarily inserted in the RV of 15 patients (68 +/- 15 years), with normal regional and global ventricular function, to record PEA at rest, during AAI pacing, during VVI pacing, and during dobutamine infusion (up to 20 micrograms/kg per min). PEA at baseline was 1.1 G +/- 0.5 (heart rate = 75 +/- 14 beats/min) and increased to 1.3 G +/- 0.9 (P = NS vs baseline) during AAI pacing (heart rate = 140 beats/min) and to 1.4 G +/- 0.5 (P = NS vs baseline) during VVI pacing (heart rate = 140 beats/min). Dobutamine infusion increased PEA to 3.7 G +/- 1.1 (P < 0.001 vs baseline), with a heart rate of 121 +/- 13 beats/min. In a subset of three patients, simultaneous hemodynamic RV monitoring was performed to obtain RV dP/dtmax, whose changes during dobutamine and pacing were linearly related to changes in PEA (r = 0.9; P < 0.001). In conclusion, the PEA recording can be consistently and safely obtained with an implantable device. Pharmacological inotropic stimulation, but not pacing induced chronotropic stimulation, increases PEA amplitude, in keeping with experimental studies, suggesting that PEA is an index of myocardial contractility. Acute variations in PEA are closely paralleled by changes in RV dP/dtmax, but are mainly determined by LV events. The clinical applicability of the method using RV endocardial leads and an implantable device offers potential for diagnostic applications in the long-term monitoring of myocardial function in man.

Meta-analysis of randomised trials comparing coronary angioplasty with bypass surgery.

A patient with severe angina will often be eligible for either angioplasty (PTCA) or bypass surgery (CABG). Results from eight published randomised trials have been combined in a collaborative meta-analysis of 3371 patients (1661 CABG, 1710 PTCA) with a mean follow-up of 2.7 years. The total deaths in the CABG and PTCA groups were 73 and 79, respectively, with a relative risk (RR) of 1.08 (95% CI 0.79-1.50). The combined endpoint of cardiac death and non-fatal myocardial infarction occurred in 169 PTCA patients and 154 CABG patients (RR 1.10 [0.89-1.37]). Amongst patients randomised to PTCA 17.8% required additional CABG within a year, while in subsequent years the need for additional CABG was around 2% per annum. The rate of additional non-randomised interventions (PTCA and/or CABG) in the first year of follow-up was 33.7% and 3.3% in patients randomised to PTCA and CABG, respectively. The prevalence of angina after one year was considerably higher in the PTCA group (RR 1.56 [1.30-1.88]) but at 3 years this difference had attenuated (RR 1.22 [0.99-1.54]). Overall there was substantial similarity in outcome across the trials. Separate analyses for the 732 single-vessel and 2639 multivessel disease patients were largely compatible, though the rates of mortality, additional intervention, and prevalent angina were slightly lower in single vessel disease. The combined evidence comparing PTCA with CABG shows no difference in prognosis between these two initial revascularisation strategies. However, the treatments differ markedly in the subsequent requirement for additional revascularisation procedures and in the relief of angina. These results will influence the choice of revascularisation procedure in future patients with angina.

Coronary angioplasty versus coronary surgery in the management of angina.

Until 1977, coronary revascularization was only possible using open surgical techniques. Approximately 10 years after the introduction of coronary angioplasty, a series of major clinical trials comparing the outcome of patients treated by surgery and angioplasty were planned and executed. The results of these trials are now becoming available and show that in patients with symptomatic disease affecting one, two, or three vessels, angioplasty is a viable alternative to surgery. From a purely medical point of view, the advantages and disadvantages of the two techniques are so finely balanced that patients preference has become an important parameter in selection of a primary intervention.

Value of physical signs in the diagnosis of ventricular tachycardia.

BACKGROUND: Although the use of physical signs for the diagnosis of ventricular tachycardia (VT) was described in the early 1900s, their value in this role has never been systematically assessed. METHODS AND RESULTS: Using a blinded, randomized protocol, we examined the ability of 26 clinicians to detect ventriculoatrial (VA) dissociation during cardiac pacing in 21 patients with both atrial and ventricular pacing wires in situ after successful ablation of accessory pathways. In protocol 1 (10 patients), pacing was randomized to either ventricular pacing alone (simulating VT) or to atrioventricular sequential pacing (simulating supraventricular tachycardia or VT with intact VA conduction) at rates of 150 or 180 beats per minute. Each patients was examined by four clinicians blinded to the pacing mode. Clinicians were asked to make a diagnosis of "VA association" or "VA dissociation" after examining the patient for variability of the arterial pulse, jugular venous pulse (JVP), and first heart sound. In protocol 2 (11 patients), randomization of pacing mode was performed between examination of each of the three physical signs so that the value of each sign was assessed individually. In protocol 1, a diagnosis of VA dissociation (VT) was made in 21 of 40 observations, with a specificity of 75%, sensitivity of 70%, and a positive predictive value (PPV) of 71%. In protocol 2, from a total of 132 observations (44 for each sign), the sensitivity, specificity, and PPV for a diagnosis of VT were as follows: arterial pulse, 61%, 71%, 70%; JVP, 96%, 75%, 82%; and first heart sound, 58%, 100%, 100%. CONCLUSIONS: It is concluded that, in patients with a regular tachycardia of uncertain origin, clinically detectable variations in the first heart sound and JVP are highly specific and sensitive indicators, respectively, of a diagnosis of VT. Assessment of the arterial pulse is of little value in this role.

Self expanding stents for the management of aorto-ostial stenoses in saphenous vein bypass grafts.

OBJECTIVE: To assess the early and follow up results of implantation of a self expanding stent in aorto-ostial stenoses of vein grafts. DESIGN: Prospective, non-randomised, observational study. SETTING: Tertiary referral centre for cardiac diseases. PATIENTS: Nineteen patients with ostial stenoses of saphenous vein grafts. MAIN OUTCOME MEASURES AND RESULTS: Stents were successfully deployed in all 19 patients with satisfactory angiographic results. In one patient this required two attempts. There were no deaths and no major procedural complications related to ostial stenting. Before discharge two (11%) patients had thrombosis of the ostial stent; one patient had a Q wave myocardial infarction. Femoral artery bleeding occurred in three (16%) patients. Angiographic follow up was performed in 18 patients at a mean of seven months. Restenosis within the ostial stent was detected in three (16%) patients. Twelve (63%) patients had an improved functional status at a mean follow up of nine months. One patient died suddenly at three months. Three (16%) patients required additional revascularisation procedures because of symptoms caused by restenosis within the ostial stent during follow up. CONCLUSIONS: Intracoronary stenting is an attractive treatment for the management of patients with vein graft ostial stenoses.

Self-expanding stents for emergency treatment of acute vessel closure following coronary angioplasty: immediate and long-term results.

Intracoronary stents may be used to treat acute coronary occlusion following balloon angioplasty. We report the immediate and long-term results of emergency implantation of the self-expanding stent (Wallstent) in 39 patients with acute vessel closure. Stents were successfully deployed in 38 patients (97%). Procedural complications occurred in 14 patients (36%); one patient died, two required emergency coronary artery bypass graft surgery, nine sustained myocardial infarcts (one Q wave), and two had acute stent thrombosis successfully treated by intracoronary thrombolysis and repeat angioplasty. Four patients (10%) had femoral artery bleeding, two required surgery. Angiographic follow-up was performed after 6 months in all 34 eligible patients, or earlier for symptoms. Two patients died prior to follow-up angiography. The stented segment was widely patent in 27 of the 34 patients (79%); restenosis within the stent was detected in 4 (12%) and thrombotic stent occlusion occurred in three (9%). Twenty-six of the 39 patients (67%) were free from major cardiac events and symptoms at 1 year. These results suggest that the self-expanding stent provides an attractive alternative to emergency surgery for the treatment of acute coronary occlusion following coronary angioplasty.

North American Society of Pacing and Electrophysiology policy statement. The NASPE/BPEG defibrillator code.

A new generic code, patterned after and compatible with the NASPE/BPEG Generic Pacemaker Code (NBG Code) was adopted by the NASPE Board of Trustees on January 23, 1993. It was developed by the NASPE Mode Code Committee, including members of the North American Society of Pacing and Electrophysiology (NASPE) and the British Pacing and Electrophysiology Group (BPEG). It is abbreviated as the NBD (for NASPE/BPEG Defibrillator) Code. It is intended for describing the capabilities and operation of implanted cardioverter defibrillators (ICDs) in conversation, record keeping, and device labeling, and incorporates four positions designating: (1) shock location; (2) antitachycardia pacing location; (3) means of tachycardia detection; and (4) antibradycardia pacing location. An additional Short Form, intended only for use in conversation, was defined as a concise means of distinguishing devices capable of shock alone, shock plus antibradycardia pacing, and shock plus antitachycardia and antibradycardia pacing.