Improved Short-Term Outcomes of Primary Coronary Stenting Compared to Primary Balloon Angioplasty in Acute Myocardial Infarction at Experienced Centers: The PAMI Study Group Experience

To study the additive benefits of routine stent implantation in patients undergoing primary percutaneous transluminal coronary angioplasty (PTCA) at experienced centers, we compared the outcomes of the 982 patients undergoing PTCA for acute myocardial infarction (AMI) in the Primary Angioplasty in Myocardial Infarction-2 (PAMI-2) trial (only 1% of whom were stented) to the 312 patients in the PAMI Stent Pilot Trial (236 [76%] of whom were stented). The inclusion and exclusion criteria, PTCA methodology, and definitions used were prespecified to be identical between the two trials. Compared to the primary PTCA approach in PAMI-2, the strategy of stenting all eligible lesions in the PAMI Stent Pilot Trial was associated with reduced rates of in-hospital death (0.6% vs 2.7%, P = 0.03), reinfarction (1.3% vs 4.6%, P = 0.008), recurrent ischemia (3.5% vs 11.6%, P < 0.0001), target vessel revascularization (7.3% vs 11.4%, P = 0.04), and a shorter hospital stay (6.4 ± 4.4 vs 7.1 ± 6.2 days, P = 0.01). By multiple logistic regression analysis in 1,294 patients, stent implantation versus PTCA only was the strongest predictor of freedom from the composite in-hospital end point of death, reinfarction, or target vessel revascularization (TVR) (8.3% vs 15.0%, multivariate odds ratio = 0.4, P < 0.0001). These data strongly suggest that despite the excellent results achieved when primary PTCA is performed by experienced operators, the short-term outcomes of mechanical reperfusion can be further improved by a primary stent strategy.     

PRELIMINARY EVALUATION OF THE ENCLOSED MAGILL BREATHING SYSTEM

The Enclosed Magill anaesthetic breathing system may be usedfor both spontaneous ventilation and controlled ventilationwith similar fresh gas flows. During spontaneous ventilation,a fresh gas flow between estimated alveolar ventilation andminute ventilation is adequate and the system performs as aMapleson A type breathing system. For controlled ventilation,a fresh gas flow of 70–100 ml kg^–1 min^–1 producesnormocapnia in most subjects, as demonstrated in this limitedstudy. These values are similar to those demonstrated for typeD breathing systems. It is suggested from this preliminary studythat the breathing system conforms to the requirements of auniversal breathing system in as much as similar fresh gas flowsare used in both modes of ventilation. ^*Present address: Department of Anaesthesia, West Mead Centre,Sydney, Australia.     

RETINOPATHY IN MICE WITH EXPERIMENTAL SCRAPIE

Scrapie is a naturally occurring neurological disease of adult sheep and goats with an incubation period of several years. Some strains of the causal agent can infect laboratory mice in which the incubation period, as well as the severity and distribution of vacuolar degeneration in the brain, varies according to the strain of the agent and the genotype of the mouse. Retinopathy, involving the partial or complete loss of the photoreceptor layer, was observed in a number of murine scrapie models but was absent in others. The severity of retinopathy depended on both the strain of scrapie and the genotype of mouse used. Some scrapie strains (22C, 87A and 87V) produced minimal or no retinal pathology, others (ME7, 22A and 22L) produced changes in the retinae of only certain mouse genotypes, while the strains 79A and 139A produced degeneration of the photoreceptor layer in every mouse genotype investigated. The severity of retinopathy in the various models did not correlate with the overall intensity of vacuolar degeneration in the brain, with the severity of vacuolation in the centres in the brain controlling pupillary constriction, or with the incubation period.     

Structural and functional changes of the gastric mucosa in rats with portal hypertension

Structural and functional changes of the gastric mucosa were studied in rats made portal hypertensive by partially ligating the portal vein. Studies were carried out at either 3 or 12 days after ligation or sham operation. At 3 days, structural changes were greater than at 12 days, the major effects being vascular congestion in the lamina propria, muscularis mucosa, submucosa, and submucosal oedema. Transmission electron microscopy showed only a mild hyperplasia in the muscularis mucosa. Gastric blood flow appeared to decrease at 3 days post-ligation compared to sham-operated control rats, but was significantly increased by 12 days after ligation (P less than 0.01). Cardiac output also appeared to increase in the portal hypertensive rats by 12 days post-ligation but this was not statistically significant. Portal venous inflow was significantly increased by 12 days (P less than 0.05) but after correction for collateral circulation liver blood flow had returned to normal values by 12 days post-ligation.     

Clinical Performance of the Implantable Cardioverter Defibrillator: Electrocardiographic Documentation of 101 Spontaneous Discharges

Records of 105 patients, who received an automatic implantable Cardioverter defibrillator (AICD), were studied to investigate the causes of spontaneous AJCD discharges and to correlate the symptoms with the arrhythmias triggering AJCD discharges. During a follow-up period of 13 ± 8 months, 46/105 (44%) patients had 566 spontaneous AICD discharges. A total of 101 discharges were documented with Holter monitoring in 23 patients. In this study group, there were 8 (8%) AICD discharges for 5 episodes of ventricular fibrillation, and 68 (67%) discharges for 63 episodes of sustained ventricular tachycardia. Patients lost consciousness in all episodes of ventricular fibrillation, but were symptomatic prior to only 36 (53%) discharges in ventricular tachycardia. Non-sustained ventricular tachycardia persisting for a period of 7,5 ± 2 seconds resulted in 20 AICD discharges; patients were symptomatic prior to 13 (65%) discharges. Supraventricular tachycardias triggered three discharges. One patient had two spurious discharges during sinus rhythm. In conclusion, most of the spontaneous AICD discharges were appropriate for the detected rhythms, but only clinically appropriate for the management of arrhythmias in 75% of the cases. A significant portion of the patients with sustained or nonsustained ventricular tachycardias triggering AICD discharges were asymptomatic prior to discharge, which requires further assessment of the physiology of the arrhythmia as a component of the detection algorithm.     

Reversible Myocardial Depression in Survivors of Cardiac Arrest

Three patients under 40-years old who survived cardiac arrest due to ventricular fibrillation were originally diagnosed as having idiopathic dilated cardiomyopathy. Shortly after cardiac arrest, assessment of myocardial function revealed a globally dilated left ventricle in each patient with an estimated ejection fraction between 20% and 30%. Serial assessment of myocardial function, however, showed either normal or near-normal function by 2 weeks postevent. These findings suggest that myocardial stunning due to hypoperfusion during ventricular fibrillation or the effects of transthoracic shocks may result in profound, reversible myocardial depression in survivors of cardiac arrest. Serial evaluation of left ventricular function may be of value in selected survivors of cardiac arrest in order to evaluate time-dependent resolution of myocardial dysfunction and may prevent misdiagnosis of idiopathic dilated cardiomyopathy.     

Electrophysiologic Basis for T Wave Alternans as an Index of Vulnerability to Ventricular Fibrillation

Electrophysiologic Basis for T Wave Alternans. Substantial evidence indicates that T wave alternans is an intrinsic property of ischemic myocardium. The electrophysiologic basis appears to be spatial and temporal heterogeneity of repolarization resulting from changes in action potential morphology rather than in activation sequence. Ischemia-induced changes in postrepolarization refractoriness and depressed electrical restitution of action potential duration have also been implicated. The main underlying ionic basis for T-wave alternans during coronary occlusion appears to be derangements in intracellular cycling of calcium. Accumulation of potassium in the extracellular space adjoining ischemic cells and disruption in electro-genie sodium-calcium exchange may also be involved. In humans, T wave alternans has been observed in Prinzmetal's and classical angina, angioplasty, and bypass graft occlusion. Under these conditions associated with acute myocardial ischemia, alternans is restricted to the ischemic zone, and alternation in action potential morphology is an underlying factor. Recently, repolarization alternans has been shown to be a statistically significant predictor of the results of electro physiologic testing and arrhythmia-free survival in individuals with and without organic heart disease. Collectively, these observations provide a rationale for quantitation of T-wave alternans magnitude for assessment of vulnerability to life-threatening ventricular arrhythmias both in response to and independent of the effects of myocardial ischemia.     

Lessons Learned from Balloon Aortic Valvuloplasty Experience from the Pre‐transcatheter Aortic Valve Implantation Era

Background: Balloon aortic valvuloplasty (BAV) has been used as a bridge to surgical aortic valve replacement (SAVR) in high‐risk patients with severe symptomatic aortic stenosis (AS). Such patients are now being referred for transcatheter aortic valve implantation (TAVI). We sought to study the indications and outcomes of BAV in patients with severe AS in the pre‐TAVI era. Methods: We analyzed consecutive patients with severe AS undergoing BAV from 1990 to 2005. In these patients with no immediate surgical option, BAV was attempted to temporarily improve hemodynamics, with a goal to improve general health of the patient, and ultimately AVR. Results : A total of 99 BAVs (eight repeats, one second repeat) were performed in 90 consecutive patients. Baseline ejection fraction was ≤25% in 36 (36%) patients. The 30‐day mortality rate was 17% (n = 17). Of the 99 patients, 27 (30%) underwent AVR. Average follow‐up of patients with and without AVR was 55 ± 57 months and 16 ± 23 months, respectively. The 6‐month and 1‐year survival rates in patients who underwent AVR were 81% and 78%, respectively, versus 57% and 44% in patients who did not undergo AVR (P = 0.024). Conclusion: BAV can be used successfully to clinically improve the health of some nonsurgical patients with severe symptomatic AS, and a proportion of these patients improve to a point where AVR can be performed. Bridging to TAVI will provide further options to high‐risk patients who cannot be bridged to conventional AVR. The role of BAV in bridging to TAVI merits further study. (J Interven Cardiol 2010;23:499–508)