Robert A. Wright

Primary percutaneous coronary intervention for acute ST-segment elevation myocardial infarction: changing patterns of vascular access, radial versus femoral artery

Objective: To examine the safety and efficacy of emergency transradial primary percutaneous coronary intervention for ST-elevation myocardial infarction. Design: Single-centre observational study with prospective data collection. Setting: A regional cardiac centre, United Kingdom. Patients: 1051 consecutive patients admitted with ST-elevation myocardial infarction, without cardiogenic shock, between November 2004 and October 2008. Interventions: Percutaneous coronary interventions by radial and femoral access Main outcome measures: The primary outcome measures were procedural success, major vascular complication and failed initial access strategy. Secondary outcomes were in-hospital mortality and major adverse cardiac and cerebrovascular events, needle-to-balloon times, contrast volume used, radiation dose absorbed and time to discharge. Multiple regression analysis was used to adjust for potential differences between the groups. Results: 571 patients underwent radial access and 480 femoral. A variable preference for radial access was observed among the lead operators (between 21% and 90%). Procedural success was similar between the radial and femoral groups, but major vascular complications were more frequent at the site of femoral access (0% radial versus 1.9% femoral, p = 0.001). Failure of the initial access strategy was more frequent in the radial group (7.7% versus 0.6%, p<0.001). Adjustment for other procedural and clinical predictors did not alter these findings. Needle-to-balloon time, as a measure of procedural efficiency, was equal for radial and femoral groups. Conclusions: In the setting of acute ST-elevation myocardial infarction without cardiogenic shock, transradial primary angioplasty is safe, with comparable outcomes to a femoral approach and a lower risk of vascular complications.

Prospective, randomised, controlled trial to study the effect of intracoronary injection of verapamil and adenosine on coronary blood flow during percutaneous coronary intervention in patients with acute coronary syndromes

Objectives: To study the impact of injection of verapamil and adenosine in the coronary arteries on TIMI (Thrombolysis in Myocardial Infarction) frame count (TFC) after percutaneous coronary intervention (PCI) in patients with an acute coronary syndrome (ACS). Methods: Prospective, randomised, controlled study of the intracoronary administration of normal saline versus verapamil versus adenosine in patients undergoing PCI in the setting of an ACS, even when flow is visually established to be normal or near normal. Patients were randomised to receive verapamil (n  =  49), adenosine (n  =  51) or normal saline (n  =  50) after PCI. Quantitative angiography, TIMI flow grade (TFG), TFC and myocardial blush grade were assessed before PCI, after PCI and after drugs were given. Wall motion index (WMI) was measured at days 1 and 30. Results: 9 patients in the verapamil group developed transient heart block, not seen with adenosine (p ⩽ 0.001). Compared with saline, coronary flow measured by TFC improved significantly and WMI improved slightly but insignificantly in both the verapamil (TFC: p  =  0.02; mean difference in improvement in WMI: 0.09, 95% confidence interval (CI) 0.015 to 0.17, p  =  0.02) and the adenosine groups (TFC: p  =  0.002; mean difference in improvement in WMI: 0.08, 95% CI 0.004 to 0.16, p  =  0.04). The improvements in TFC and WMI did not differ significantly between the verapamil and the adenosine groups (TFC: p  =  0.2; mean difference in improvement in WMI: 0.01, 95% CI −0.055 to 0.08, p  =  0.7, respectively). Conclusion: Administration of verapamil or adenosine significantly improves coronary flow and WMI after PCI in the setting of an ACS. Flow and WMI did not differ significantly between verapamil and adenosine but verapamil was associated with the development of transient heart block.

Differing patterns of cardiac parasympathetic activity and their evolution in selected patients with a first myocardial infarction

OBJECTIVES The purpose of the study was to compare cardiac parasympathetic activity during the early and convalescent phases of acute anterior and inferior myocardial infarction. BACKGROUND Previous studies have shown that cardiac parasympathetic activity may vary with the site of infarction and that recovery may occur after infarction. METHODS Cardiac parasympathetic activity was measured from 24-h electrocardiograms by counting the number of times that successive RR intervals (counts) differed by > 50 ms. Recordings began within 12 h of admission and at 7, 42 and 140 days after acute myocardial infarction in 20 patients (mean age 57 +/- 7.9 years). All patients were treated with streptokinase, aspirin and oral beta-adrenergic blocking agents. RESULTS For the entire group, mean total 24-h RR counts increased from 592 (range 78 to 3,812) at 48 h to 648 (range 109 to 5,473) at 7 days, 1,145 (range 162 to 6,268) at 42 days and 1,958 (range 344 to 9,632) at 140 days. Patients with anterior infarction had significantly lower counts (mean 277, range 78 to 2,708; n = 11) compared with those with inferior infarction (mean 2,172, range 897 to 3,812; n = 9) at 48 h (p < 0.05). There was no significant difference in counts between patients with anterior (mean 1,051, range 212 to 6,268) and inferior (mean 1,321, range 162 to 3,265) infarction after 42 or after 140 days (anterior: mean 1,655, range 344 to 9,632; inferior: mean 2,588, range 1,700 to 5,767). CONCLUSIONS These data suggest that after anterior myocardial infarction there is impaired cardiac parasympathetic function that improves within 6 weeks, whereas in inferior infarction there is relative preservation of cardiac parasympathetic function.

Cumulative funnel plots for the early detection of interoperator variation: retrospective database analysis of observed versus predicted results of percutaneous coronary intervention

Objective To use funnel plots and cumulative funnel plots to compare in-hospital outcome data for operators undertaking percutaneous coronary interventions with predicted results derived from a validated risk score to allow for early detection of variation in performance. Design Analysis of prospectively collected data. Setting Tertiary centre NHS hospital in the north east of England. Participants Five cardiologists carrying out percutaneous coronary interventions between January 2003 and December 2006. Main outcome measures In-hospital major adverse cardiovascular and cerebrovascular events (in-hospital death, Q wave myocardial infarction, emergency coronary artery bypass graft surgery, and cerebrovascular accident) analysed against the logistic north west quality improvement programme predicted risk, for each operator. Results are displayed as funnel plots summarising overall performance for each operator and cumulative funnel plots for an individual operator’s performance on a case series basis. Results The funnel plots for 5198 patients undergoing percutaneous coronary interventions showed an average observed rate for major adverse cardiovascular and cerebrovascular events of 1.96% overall. This was below the predicted risk of 2.06% by the logistic north west quality improvement programme risk score. Rates of in-hospital major adverse cardiovascular and cerebrovascular events for all operators were within the 3σ upper control limit of 2.75% and 2σ upper warning limit of 2.49%. Conclusion The overall in-hospital major adverse cardiovascular and cerebrovascular events rates were under the predicted event rate. In-hospital rates after percutaneous coronary intervention procedure can be monitored successfully using funnel and cumulative funnel plots with 3σ control limits to display and publish each operator’s outcomes. The upper warning limit (2σ control limit) could be used for internal monitoring. The main advantage of these charts is their transparency, as they show observed and predicted events separately. By this approach individual operators can monitor their own performance, using the predicted risk for their patients but in a way that is compatible with benchmarking to colleagues, encapsulated by the funnel plot. This methodology is applicable regardless of variations in individual operator case volume and case mix.

Cardiac catheterisation: radiation doses and lifetime risk of malignancy.

Cardiac catheterisation and angiography uses ionising radiation and therefore produces a radiation dose to the patient and to the operating staff. The dose to the patient can be measured using thermoluminescent dosemeters placed on the skin or by using a large-area detector attached to the x ray tube to measure the dose–area product (DAP) for the incident x ray beam (DAP meter). The DAP is particularly useful for assessing and comparing the radiation dose from screening procedures. It provides a more useful indication of the overall patient exposure than measurement of surface dose at particular locations. The dose measurement is used either as a surrogate for radiation risk or as a step in actually estimating the risk. Published factors allow conversion of the DAP to effective dose, a derived quantity in which doses to different organs or tissues are weighted according to their radiosensitivity and summed to give a risk-related dose quantity.1–5 UK legislation does not give dose limits for patients undergoing medical diagnostic exposures, but requires adherence to the “as low as reasonably practicable” principle, and comparison of doses with diagnostic reference levels for common procedures. Published data for patient exposure, absorbed dose, effective dose and risk of malignancy from the different specific diagnostic cardiac catheterisation procedures are incomplete, and there are no national diagnostic reference levels for individual procedures. We undertook this study with the aim of establishing local patient doses for six different diagnostic cardiac catheterisation procedures …

Predictors of outcome after percutaneous treatment for cardiogenic shock

Objectives: To determine predictors of outcome after percutaneous coronary intervention (PCI) in patients with cardiogenic shock complicating acute myocardial infarction. Methods: Retrospective analysis of a cohort of 113 patients undergoing emergency coronary angiography and attempted PCI for cardiogenic shock complicating acute myocardial infarction in a regional cardiothoracic unit. Results: In-hospital mortality was 51% (58 patients). Adverse outcome was associated with previous myocardial infarction, age over 70 years, cardiogenic shock complicating failure to respond to thrombolytic treatment (failed thrombolysis), and multivessel coronary artery disease. Multivariate logistic regression analysis showed that the first three factors were independent predictors of in-hospital death with odds ratios of 5.21 (95% confidence interval (CI) 1.85 to 14.69), 4.02 (95% CI 1.14 to 14.12), and 3.78 (95% CI 1.43 to 9.96), respectively. Conclusion: About 50% of patients with cardiogenic shock undergoing a strategy of urgent coronary angiography and PCI survive to hospital discharge. Survivors do well in the subsequent six months. Emergency PCI for cardiogenic shock reduces mortality from an expected 80% to about 50%. Clinical features can help determine which patients are most likely to gain from urgent coronary angiography and attempted PCI. Alternative strategies are needed to improve the outcome of patients who fare badly.

One year results of the Middlesbrough early revascularisation to limit infarction (MERLIN) trial

Objective: To report one year results of the MERLIN (Middlesbrough early revascularisation to limit infarction) trial, a prospective randomised trial comparing the strategy of coronary angiography and urgent revascularisation with conservative treatment in patients with failed fibrinolysis complicating ST segment elevation myocardial infarction (STEMI). The 30 day results have recently been published. At the planning stage of the trial, it was determined that follow up of trial patients would continue annually to three years to determine whether late benefit occurred. Subjects: 307 patients who received a fibrinolytic for STEMI but failed to reperfuse early according to previously described ECG criteria and did not develop cardiogenic shock. Methods: Patients were randomly assigned to receive either emergency coronary angiography with a view to proceeding to urgent revascularisation (rescue percutaneous coronary intervention (rPCI) arm) or continued medical treatment (conservative arm). The primary end point was all cause mortality at 30 days. The secondary end points included the composite end point of death, reinfarction, stroke, unplanned revascularisation, or heart failure at 30 days. The same end points were evaluated at one year and these results are presented. Results: All cause mortality at one year was similar in the conservative arm and the rPCI arm (13.0% v 14.4%, p  =  0.7, risk difference (RD) −1.4%, 95% confidence interval (CI) −9.3 to 6.4). The incidence of the composite secondary end point of death, reinfarction, stroke, unplanned revascularisation, or heart failure was significantly higher in the conservative arm (57.8% v 43.1%, p  =  0.01, RD 14.7%, 95% CI 3.5% to 25.5%). This was driven almost exclusively by a significantly higher incidence of subsequent unplanned revascularisation in the conservative arm (29.9% v 12.4%, p < 0.001, RD 17.5%, 95% CI 8.5% to 26.4%). Reinfarction and clinical heart failure were numerically, but not statistically, more common in the conservative arm (14.3% v 10.5%, p  =  0.3, RD 3.8%, 95% CI −3.7 to 11.4, and 31.2% v 26.1%, p  =  0.3, RD 5.0%, 95% CI −5.1 to 15.1). There was a strong trend towards fewer strokes in the conservative arm (1.3% v 5.2%, p  =  0.06, RD −3.9%, 95% CI −8.9 to 0.06). Conclusion: At one year of follow up, there was no survival advantage in the rPCI arm compared with the conservative arm. The incidence of the composite secondary end point was significantly lower in the rPCI arm, but this was driven almost entirely by a highly significant reduction in the incidence of further revascularisation.

Corrected TIMI frame count: applicability in modern digital catheter laboratories when different frame acquisition rates are used.

The original description of the TIMI frame count (TFC) method was based on angiograms acquired at 30 f/sec. Modern digital angiograms are acquired at lower frame rates (between 12.5 and 25 f/sec). Coronary angiography was acquired at 12.5 and 25 f/sec after 200 μg of intracoronary glyceryl trinitrate. Results of the corrected TIMI frame count (cTFC) at 12.5 and 25 f/sec for each vessel were: right coronary artery, 19.5 ± 5.2 and 20.4 ± 6.6 (P = 0.15); circumflex artery, 25.6 ± 8.2 and 25.9 ± 8.7 (P = 0.5); and left anterior descending artery, 22.5 ± 8.1 and 23.8 ± 10.4 (P = 0.15), respectively. The mean difference in the TFC between two injections by the same operator and by two operators was 0.4 (P = 0.7) and 0.4 (P = 0.2), respectively. The mean difference in the TFC for repeat measurements by the same observer and between two observers was 0.26 (P = 0.3) and 0.06 (P = 0.8), respectively. We confirm that the cTFC is a quantitative method to assess coronary flow that can be applied in a modern digital laboratory. Catheter Cardiovasc Interv 2004;63:426–432.

Effects of digoxin on time domain measures of heart rate variability in patients with stable chronic cardiac failure: withdrawal and comparison group studies

The effect on heart rate variability of adding digoxin to a diuretic and ACE inhibitor was studied in patients with chronic stable cardiac failure. Digoxin was found to increase heart rate variability, especially those measures of heart rate variability thought to represent parasympathetic activity. The withdrawal of digoxin led to a decrease in heart rate variability to pre-treatment levels. Whilst digoxin in standard doses does not alter prognosis in chronic cardiac failure, it does have potentially beneficial neurohumoral effects. If the increase in heart rate variability, which represents beneficial neurohumoral modulation, can be divorced from the potentially detrimental effects, perhaps by using smaller doses, then there may be a role for digoxin in the treatment of chronic cardiac failure.

External Validation of Established Risk Adjustment Models for Procedural Complications after Percutaneous Coronary Intervention

Background: Workable risk models for patients undergoing percutaneous coronary intervention (PCI) are needed urgently. Objective: To validate two proposed risk adjustment models (Mayo Clinic Risk Score (MC), USA and North West Quality Improvement Programme (NWQIP), UK models) for in-hospital PCI complications on an independent dataset of relatively high risk patients undergoing PCI. Setting: Tertiary centre in northern England. Methods: Between September 2002 and August 2006, 5034 consecutive PCI procedures (validation set) were performed on a patient group characterised by a high incidence of acute myocardial infarction (MI; 16.1%) and cardiogenic shock (1.7%). Two external models—the NWQIP model and the MC model—were externally validated. Main outcome measure: Major adverse cardiovascular and cerebrovascular events: in-hospital mortality, Q-wave MI, emergency coronary artery bypass grafting and cerebrovascular accidents. Results: An overall in-hospital complication rate of 2% was observed. Multivariate regression analysis identified risk factors for in-hospital complications that were similar to the risk factors identified by the two external models. When fitted to the dataset, both external models had an area under the receiver operating characteristic curve ⩾0.85 (c index (95% CI), NWQIP 0.86 (0.82 to 0.9); MC 0.87(0.84 to 0.9)), indicating overall excellent model discrimination and calibration (Hosmer–Lemeshow test, p>0.05). The NWQIP model was accurate in predicting in-hospital complications in different patient subgroups. Conclusions: Both models were externally validated. Both predictive models yield comparable results that provide excellent model discrimination and calibration when applied to patient groups in a different geographic population other than that in which the original model was developed.