[Mortality of myocardial infarction]. / La mortalité des syndromes coronariens aigus.

Coronary disease is a major cause of death and disability. From 1975 to 2000, coronary mortality was reduced by half. Better treatments and reduction of risk factors are the main causes. This phenomenon is observed in most developed countries, but mortality from coronary heart disease continues to increase in developing countries. In-hospital mortality of ST elevation myocardial infarction (STEMI) is in the range of 7 to 10% in registries. In infarction without ST segment elevation (NSTEMI), in-hospital mortality is around 5%. More recent studies found a similar in-hospital mortality for STEMI and NSTEMI. Because of patient selection and monitoring, mortality in clinical trials is much lower. After adjustment for the extent of coronary disease, age, risk factors, history of myocardial infarction, the excess mortality observed in women is fading. Many clinical, biological and laboratory parameters are associated with mortality in myocardial infarction. They refer to the immediate risk of death (ventricular rhythm disturbances, shock…), the extent of infarction (number of leads with ST elevation on the ECG, release of biomarkers, ejection fraction…), the presence of heart failure, the failure of reperfusion and the patient's baseline risk (age, renal function…). Risk scores, and more specifically the GRACE risk score, synthesize these different markers to predict the risk of death in a given patient. However, their use for the treatment of myocardial only concerns NSTEMI. Only a limited number of mechanical or pharmacological interventions reduces mortality of heart attack. The main benefits are observed with reperfusion by thrombolysis or primary angioplasty in STEMI, aspirin, heparin, beta-blockers, angiotensin converting enzyme inhibitors. Some medications such as bivalirudin and fondaparinux reduce mortality by decreasing the incidence of hemorrhagic complications. The guidelines classify interventions according to their benefit and especially their ability to reduce mortality. Organized care systems that improve implementation of guidelines also reduce mortality. Finally, some new therapeutic approaches such as post-conditioning and new therapeutic classes offer encouraging prospects for further reducing the mortality of myocardial infarction.

Presence and extent of cardiac magnetic resonance microvascular obstruction in reperfused non-ST-elevated myocardial infarction and correlation with infarct size and myocardial enzyme release.

OBJECTIVE: Microvascular obstruction (MO) is a factor of adverse outcome in patients with ST-elevated myocardial infarction (STEMI). We assessed the presence and extent of MO and its relationship with infarct size and left ventricular (LV) functional parameters after acute non-ST-elevated myocardial infarction (NSTEMI). METHODS: Twenty-five patients with first acute NSTEMI underwent a cine and first-pass perfusion cardiac magnetic resonance (CMR) study, with late gadolinium enhancement imaging 72 h after myocardial infarction. RESULTS: MO was detected in 32% of patients, and its extent comprised 0.5-3.1% of the total LV mass (mean 1.9 +/- 1.2%). Patients with MO had a significantly larger infarct size than patients without (14.1 +/- 5.9 vs. 5.3 +/- 4.1% LV mass; p < 0.001). There was no significant difference between both groups for the LV functional parameters and LV ejection fraction (58.5 +/- 6.8 vs. 62.6 +/- 9.6%; p = 0.29). Patients with MO showed a higher troponin I release (570 +/- 364 vs. 148 +/- 103 IU; p = 0.003) and a higher creatine kinase release (29,887 +/- 18,263 vs. 10,287 +/- 5,283 IU; p = 0.007). CONCLUSIONS: In patients with acute NSTEMI, MO has a frequency similar to that observed in patients with STEMI and also correlates with the infarct extent. The prognostic significance on clinical outcome remains to be shown in this specific population.

Acute myocarditis mimicking lateral myocardial infarction.

We report a case of myocarditis mimicking acute lateral myocardial infarction and treated as such initially, which was complicated by ventricular fibrillation a few hours after admission to the intensive care unit. The correct diagnosis was rapidly made using a low-dose delayed-enhanced cardiac multidetector computed tomography scan performed immediately after a normal coronary angiogram, demonstrating typical myocardial late hyperenhancement and good correlation with delayed enhanced magnetic resonance imaging. This case suggests that myocarditis can be accurately diagnosed by delayed-enhanced cardiac multidetector computed tomography in an emergency setting. The other lesson from this case is that patients presenting with severe clinical symptoms, important ECG signs and high myocardial enzyme levels should be closely monitored for at least 72 hours, even when myocardial infarction has been excluded.

[Ictero-haemorrhagic leptospirosis with a cardiac presentation in a patient returning from an endemic zone]. / Leptospirose ictéro-hémorragique de presentation cardiaque chez une patiente de retour de zone d'endémie.

On returning from a tropical area, the occurrence of rapidly evolving cardiogenic shock in an infectious context should quickly suggest the diagnosis, for which specific treatment can affect the outcome. The dramatic case of a young female presenting with ictero-haemorrhagic leptospirosis diagnosed post-mortem, demonstrated this pathology with the unusual association of complete atrio-ventricular block and myocarditis in a haemorrhagic context.

Non-invasive testing of acquired long QT syndrome: evidence for multiple arrhythmogenic substrates.

BACKGROUND: Although well-defined clinically and electrocardiographically, Acquired Long QT Syndrome (LQTS) remains elusive from a pathophysiologic point of view. An increasingly accepted hypothesis is that it represents an attenuated form of Congenital Long QT Syndrome. To test this hypothesis further, we investigated patients with Acquired LQTS, using various investigations that are known to give information in patients with Congenital LQTS. METHODS: All the investigations were performed in patients with a history of Acquired Long QT Syndrome, defined by marked transient QT lengthening (QT>600 ms) and/or torsades de pointes. Measurement of the QT interval dispersion, the interlead difference for the QT interval on a 12-lead ECG, was performed in 18 patients and compared with 18 controls, matched for age and sex. To assess sympathetic myocardial innervation, I-123 Meta-iodobenzylguanidine (I-123-MIBG) scintigraphy was performed in 12 patients, together with Thallium scintigraphy, to rule out abnormal myocardial perfusion. Time-frequency analysis of a high-resolution ECG using a wavelet technique, was made for nine patients and compared with 38 healthy controls. Finally, genetic studies were performed prospectively in 16 consecutive patients, to look for HERG, KCNE1, KCNE2 and KCNQ1 mutations. The functional profile of a mutated HERG protein was performed using the patch-clamp technique. RESULTS: Compared with the control group, a significant increase in QT dispersion was observed in the patients with a history of Acquired LQTS (55+/-15 vs. 33+/-9 ms, P<0.001). In another group of patients with Acquired LQTS, 123 I-MIBG tomoscintigraphy demonstrated a decrease in the sympathetic myocardial innervation. Time--frequency analysis using wavelet transform, demonstrated an abnormal frequency content within the QRS complexes, in the patients with Acquired LQTS, similar to that found in Congenital LQTS patients. Molecular screening in 16 consecutive patients, identified one patient with a missense mutation on HERG, one of the LQTS genes. Expression of the mutated HERG protein led to altered K(+) channel function. CONCLUSION: Our results suggest that Acquired and Congenital Long QT Syndromes have some common features. They allow the mechanism of the clinical heterogeneity, found in both syndromes, to be understood. Further multi-facet approaches are needed to decipher the complex interplay between the main determinants of these arrhythmogenic diseases.

Influence of atrial flutter ablation on right to left inter-atrial conduction.

AIMS: Ablation of the atrial isthmus between the tricuspid annulus and the inferior vena cava changes P-wave morphology during low lateral right atrial pacing. For better understanding of the mechanism of this alteration, the sequence of activation of the inter-atrial septum and the left atrium were compared before and after ablation of the isthmus between the inferior vena cava and the tricuspid annulus. METHODS AND RESULTS: In 13 patients, left atrial mapping was performed using a duodecapolar electrode catheter advanced to the far distal coronary sinus. The inter-atrial septum was mapped using a right atrial duodecapolar electrode catheter. Conduction times were measured during low lateral right atrial pacing from the pacing artefact and during sinus rhythm from the earliest right atrial electrogram to every intra-cardiac electrogram before and after the ablation. During low lateral right atrial pacing, isthmus ablation resulted in a significant delay in every left atrial lead. Changes were maximal at the posterior aspect of the left atrium and minimal at its anterior aspect. No significant change was discernible on the inter-atrial septum. During sinus rhythm, atrial activations remained unchanged. CONCLUSION: Electrocardiographic changes of P-wave morphology result from alteration in the sequence of left atrial activation rather than that of the inter-atrial septum.

Cardiac pacemakers. When clinical evaluation lags behind technological progress.

OBJECTIVE: The rise in the number of implantations of cardiac pacemakers is of some concern to decision makers in the health sector. We assessed the intrinsic and relative clinical efficacy of cardiac pacemakers in current clinical indications to find out whether scientific or clinical arguments might justify differences in market prices. METHODS: We retrieved papers on cardiac pacing (January 1993-April 1998) from five databases (MEDLINE, HealthSTAR, EMBASE, Cochrane Library, and PASCAL). The citations in these papers were used to seek further articles. We selected the articles that met the criteria of evidence-based medicine (EBM) (randomized and nonrandomized controlled trials) and classified them according to clinical indication and type of evaluation (either of the intrinsic efficacy of a pacemaker versus a control or of the relative efficacy of different pacing modes). RESULTS: A total of 542 references were retrieved, but under 10% met our EBM criteria. Very few were comparative studies versus controls; most were recent and tended to use endpoints other than survival. Clinical efficacy was not proven on the basis of EBM criteria, even in common indications (e.g., sick sinus syndrome). Studies comparing different pacing modes were rarely randomized and did not provide consistent evidence for the superiority of any pacing mode in a given indication. CONCLUSIONS: Knowledge of the natural history of the diseases for which cardiac pacing is indicated is scarce. There is an approximately 20-year gap between technological progress and clinical evaluation that cannot be easily bridged because of methodologic difficulties and ethical issues. Current guidelines on pacemaker use either rely on expert opinion or highlight present inadequacies and make recommendations for future work. Available clinical efficacy data do not justify the wide differences in the price of cardiac pacemakers.

[Acute dissection of the ascending thoracic aorta complicated by myocardial infarct: an unavoidable diagnostic pitfall?]. / Dissection aiguë de l'aorte thoracique ascendante compliquée d'infarctus du myocarde: un piège diagnostique inévitable?

BACKGROUND: Acute dissection of the aorta during myocardial infarction is exceptional. In such cases, fibrinolysis can be fatal. CASE REPORTS: A 63-year-old woman with a history of hypertension was referred to our intensive care unit with the diagnosis of early stage inferior myocardial infarction. Thrombolysis was instituted and the patient rapidly developed cardiovascular collapse with global heart failure. Coronarography was attempted to revascularize the occluded coronary artery but the coronary arteries could not be catheterized. An aortography was performed and gave the diagnosis of De Bakey type I dissection of the aorta. The patient died from cardiac arrest after a phase of low cardiac output. DISCUSSION: This case illustrates how myocardial infarction can complicate or mask acute dissection of the aorta. It also raises the question of transthoracic echocardiography prior to institution of fibrinolysis.

Serum cardiac troponin I and ST-segment elevation in patients with acute pericarditis.

OBJECTIVE: ST-segment elevation in acute pericarditis is believed to be caused by superficial myocardial inflammation or epicardial injury. We used cardiac troponin I, a sensitive and specific marker of myocardial injury, to assess myocardial lesions in idiopathic acute pericarditis and its relationship to ST-segment elevation. PATIENTS AND METHODS: Sixty-nine consecutive patients (53 men, 48+/-17 years) with idiopathic acute pericarditis were included. We used an enzymoimmunoflurometric method to measure serum cardiac troponin I on admission (myocardial infarction threshold was 1.5 ng. ml(-1)). RESULTS: Cardiac troponin I was detectable in 34 patients (49%) and was beyond the 1.5 ng. ml(-1)threshold in 15 (22%). Coronary angiography performed in seven of these 15 patients was normal in all of them. ST-segment elevation was observed in 93% of the patients with cardiac troponin I >1.5 ng. ml(-1)vs 57% of those without (P<0.01). Sensitivity of ST-segment elevation to detect myocardial injury was 93% and specificity 43%. Patients with a cardiac troponin I increase higher than 1.5 ng. ml(-1)were more likely to have had a recent infection (66% vs 31%;P=0.01) and were younger (37+/-14 vs 52+/-16 years;P=0.002). There was no significant relationship with other parameters such as pericardial friction rub, fever, PR segment abnormalities, echocardiographic findings or C-reactive protein. CONCLUSION: In patients with idiopathic acute pericarditis, an increase in cardiac troponin I is frequently observed, especially in younger patients and those with a recent infection. Although ST-segment elevation does not reliably indicate myocardial injury, a significant cardiac troponin I increase is only seen in these patients.

[Secondary infections after pacemaker implantation]. / Infections secondaires à l'implantation d'un pacemaker.

INTRODUCTION: Infectious complications following pacemaker implantation are not common but may be particularly severe. Localized wound infections at the site of implantation have been reported in 0.5% of the cases in the most recent series, with an average of about 2%. The incidence of septicemia and infectious endocarditis is lower, about 0.5% of the cases. The operator's experience, the duration of the procedure and repeat procedures are considered to be predisposing factors. CURRENT KNOWLEDGE AND KEY POINTS: The main cause of these infections has been recently demonstrated to be local contamination during implantation. The commonest causal organism is Staphylococcus (75 to 92% of the cases), Staphylococcus aureus being the cause of acute infections (less than 6 weeks), whereas Staphylococcus epidermidis is associated with cases of secondary infection (more than 2 months). The usual clinical presentation is infection at the site of the pacemaker but other forms such as abscess, endocarditis, rejection of the implanted material, septic emboli or phlebitis have been described. The diagnosis is confirmed by local and systemic biological investigations and by echocardiography (especially transesophageal echocardiography) in cases of right heart endocarditis. There are two axes of treatment: bactericidal double antibiotherapy and surgical ablation of the infected material either percutaneously or by cardiotomy. FUTURE PROSPECTS AND PROJECTS: A recent meta-analysis supported the role of systematic, preoperative, prophylactic antibiotic therapy in the prevention of these complications. These data should be confirmed by suitably powered clinical trials.

Gated blood-pool SPECT evaluation of changes after radiofrequency catheter ablation of accessory pathways: evidence for persistent ventricular preexcitation despite successful therapy.

OBJECTIVES: This study was designed to prospectively evaluate the effects of radiofrequency ablation in Wolff-Parkinson-White (WPW) syndrome by scintigraphic analysis. BACKGROUND: The functional changes triggered by radiofrequency current ablation of atrioventricular accessory pathways are not fully known. METHODS: Forty-four patients with WPW syndrome were consecutively investigated before and 48 h after radiofrequency therapy. Fourteen patients had right sided atrioventricular pathways and 30 patients had left sided bypass-tracts. Planar gated imaging and gated blood pool tomography were performed in all of these patients. RESULTS: A significant increase in the left ventricular ejection fraction (LVEF) was demonstrated in patients with left preexcitation (62.2+/-7.9% before ablation against 64.4+/-6.3% after ablation, p = 0.02) but not for those with right sided anomalous pathway. Phase analysis only gave significant differences following ablation of right sided pathways (left-to-right phase difference = 14.4+/-13.8 degrees before ablation versus 7.5+/-7.2 degrees after ablation, p<0.05). Early abnormal ventricular contraction persisted in 12 patients with right accessory pathways and in 8 patients with left accessory pathways despite the complete disappearance of any abnormal conduction as proven electrophysiologically. CONCLUSIONS: Following catheter ablation of atrioventricular accessory pathways: 1) an improvement of left ventricular function may be seen, particularly in patients with left sided accessory pathways, and 2) unexpected persistence of local ventricular preexcitation at the site of successful ablation may be detected.

Accuracy and limitations of published algorithms using the twelve-lead electrocardiogram to localize overt atrioventricular accessory pathways.

INTRODUCTION: The purpose of this study was to evaluate the accuracy and limitations of published algorithms using the 12-lead ECG to localize AV accessory pathways (APs). METHODS AND RESULTS: The 11 relevant algorithms found in the literature (MEDLINE database and major scientific sessions) were tested on a series of 266 consecutive patients who successfully underwent radiofrequency catheter ablation of a single overt AV AP. The positive predictive values (PPV) of the algorithms in applicable patients were significantly lower for algorithms with > 6 accessory location sites (40.6% +/- 10.9% vs 61.2% +/- 8.0%; P < 0.03) and show a tendency for algorithms not relying on delta wave polarity but on QRS polarity only (36.6% +/- 11.2% vs 52.3% +/- 13.1%; P = 0.09). The PPV in applicable patients is related to the AP location (P < 0.001) and ranked from the highest to the lowest as follows: left lateral (mean PPV = 86.3%), posteroseptal (mean PPV = 65.2%), right anteroseptal (mean PPV = 45.2%), and right posterolateral (mean PPV = 23.4%). CONCLUSION: Our study suggests that the accuracy of algorithms relying on the 12-lead ECG depends on AP locations as defined in the algorithms and on the number of AP sites. The accuracy tends to be lower when delta wave polarity is not included in the algorithm's architecture. This should be considered when using these algorithms or when building new ones.

Thoracoscopic epicardial radiofrequency ablation for vagal atrial fibrillation in dogs.

Epicardial radiofrequency catheter ablation of the atria in the open-chest dog has been shown to reduce inducibility of atrial fibrillation. Video-assisted endoscopic techniques decrease the operative trauma in adult thoracic surgery. We report our results of video-assisted thoracoscopic radiofrequency catheter ablation of the atria for the prevention of atrial fibrillation induction in canines. In 12 consecutive anesthetized dogs, induction of sustained atrial fibrillation was reproducibly obtained by burst pacing and cervical vagal stimulation. In six dogs, biatrial ablation was performed through right and left minithoracotomies and guided by video-assisted endoscopic techniques. The remaining six dogs underwent a video-guided left atrial procedure. Long continuous and transmural lesions were produced using epicardial temperature controlled radiofrequency energy delivery according to a simplified maze approach. Transmural lesions were demonstrated at the end of the study by examination of the heart. Sustained atrial fibrillation was still inducible after the right atrial ablation but sustained atrial fibrillation could not be induced following left atrial ablation. In acute canine studies: (1) epicardial radiofrequency catheter ablation of the atria is feasible using video-assisted endoscopic techniques; (2) ablation extended or confined to the left atrium appears to be effective in preventing the inducibility of sustained vagal atrial fibrillation; and (3) ablation of the right atrium alone had no antiarrhythmic effect.

Selective effects of methylphenidate in attention deficit hyperactivity disorder: a functional magnetic resonance study.

Functional MRI revealed differences between children with Attention Deficit Hyperactivity Disorder (ADHD) and healthy controls in their frontal-striatal function and its modulation by methylphenidate during response inhibition. Children performed two go/no-go tasks with and without drug. ADHD children had impaired inhibitory control on both tasks. Off-drug frontal-striatal activation during response inhibition differed between ADHD and healthy children: ADHD children had greater frontal activation on one task and reduced striatal activation on the other task. Drug effects differed between ADHD and healthy children: The drug improved response inhibition in both groups on one task and only in ADHD children on the other task. The drug modulated brain activation during response inhibition on only one task: It increased frontal activation to an equal extent in both groups. In contrast, it increased striatal activation in ADHD children but reduced it in healthy children. These results suggest that ADHD is characterized by atypical frontal-striatal function and that methylphenidate affects striatal activation differently in ADHD than in healthy children.

Hypertrophic cardiomyopathy and pregnancy.

The case of a young primiparous woman with defibrillator-assisted familial hypertrophic cardiomyopathy (HCM) has led us to review the literature on this pathology, which is exceptional because of its scarcity and the originality of the problems encountered. To our knowledge, this is the first observation ever reported of defibrillator-assisted activation during pregnancy in a woman with HCM. Several questions raised from this particular case, e.g. what are the risks caused by pregnancy in these patients, what is the impact of therapeutics, does the activation of an internal defibrillator involve particular risks, what is the best disposition for delivery and what are the risks for fetuses? We have tried to ask all of these questions, using as exhaustive a literature review as possible.

Troponin I, troponin T, or creatine kinase-MB to detect perioperative myocardial damage after coronary artery bypass surgery.

STUDY OBJECTIVES: To compare cardiac troponin I (cTnI), cardiac troponin T (cTnT), and creatine kinase MB (CKMB mass) in patients with and without new Q wave on the ECG following coronary artery bypass graft (CABG) surgery. PATIENTS: After ethic committee's approval and informed consent, 82 patients, mean age 63+/-10 years, scheduled for CABG were included. INTERVENTIONS: Arterial blood samples were drawn during cardiopulmonary bypass, before, and 6, 12, 24, and 48 h after aortic cross-clamp release. cTnI, cTnT, and CKMB mass were measured. The appearance of new Q wave on the ECG performed preoperatively and 24 h postoperatively was used to assess myocardial lesion independently of biological markers. RESULTS: There were 69 patients without new Q wave on the ECG (group 1) and 13 with (group 2). In group 1, cTnI reached a peak of 2.1 microg/L (median, interquartile range [IQ]=2.4) at 12 h, cTnT increased progressively with a peak of 0.22 microg/L (IQ=0.2) at 48 h, and CKMB presented an earlier peak of 10 microg/L (IQ=6.2) at 6 h. Starting with the same median value, group 2 patients presented significantly higher peaks: cTnI: 17 microg/L (IQ=16) at 12 h; cTnT: 1.4 microg/L (IQ=2.3) at 12 h; and CKMB mass: 74 microg/L (IQ=61) at 6 h. Receiver operating characteristic (ROC) curves were constructed. The area under the curve was 0.90 for cTnI, 0.84 for CKMB, and 0.81 for cTnT (not significant). The best cutoff values to discriminate between group 1 and group 2 patients were determined with the ROC curves: cTnI=5 microg/L; CKMB mass=20 microg/L; cTnT=0.3 microg/L. Sensitivity, specificity, and positive and negative values for cTnI (5 microg/L) were 91%, 82%, 53%, and 98%, respectively. CONCLUSIONS: There was little differences among cTnI, cTnT, and CKMB after CABG to diagnose myocardial damage as assessed by new Q wave on the ECG. There was a trend of cTnI to be a better discriminator than cTnT, but it did not reach statistical significance.

[Infections secondary to implantation of cardiac pacemakers]. / Infections secondaires à l'implantation d'un stimulateur cardiaque.

Infectious complications of pacemaker implantation are not common but may be particularly severe. Localised wound infections at the site of implantation have been reported in 0.5% of cases in the most recent series with an average of about 2%. The incidence of septicaemia and infectious endocarditis is lower, about 0.5% of cases. The operator's experience, the duration of the procedure and repeat procedures are considered to be predisposing factors. The main cause of these infections is though to be local contamination during the implantation. The commonest causal organism is the staphylococcus (75 to 92%), the staphylococcus aureus being the cause of acute infections whereas the staphylococcus epidermis is associated with cases of secondary infection. The usual clinical presentation is infection at the site of the pacemaker but other forms such as abscess, endocarditis, rejection of the implanted material, septic emboli and septic phlebitis have been described. The diagnosis is confirmed by local and systemic biological investigations and by echocardiography (especially transoesophageal echocardiography) in cases of right heart endocarditis. There are two axes of treatment: bactericidal double antibiotherapy and surgical ablation of the infected material either percutaneously or by cardiotomy. Though controversial, and unsupported by scientific evidence, the role of systematic, preoperative, prophylactic antibiotic therapy in the prevention of these complications seems to be increasing.

Safety and tolerability of intravenous cibenzoline for acute termination of spontaneous sustained ventricular tachycardia. Cibenzoline and spontaneous VT.

STUDY OBJECTIVES: To evaluate prospectively, the tolerability and safety of intravenous cibenzoline therapy, for the cardioversion of spontaneous monomorphic ventricular tachycardia (VT). SETTING AND PATIENTS: Between February 1990 and December 1996, fifty-eight patients aged 59+/-10 years old (fifty-three males, five females), with spontaneous VT not causing cardiac arrest, received intravenous cibenzoline. Their underlying heart conditions were: ischemic heart disease [35], dilated cardiomyopathy [14], right ventricular dysplasia [3], hypertrophic cardiomyopathy [1], valvulopathy [2], Fallot's Tetralogy [1] and primary arrhythmogenic disease [2]. The left ventricular ejection fraction was 42+/-13% (range 20%-76%). RESULTS: The mean dose of cibenzoline was 70+/-12 mg. The tachycardia stopped within 6+/-3 min in 47 (81%) patients. Side effects from cibenzoline occurred in two patients. The hemodynamic complications were limited to hypotension, that required vasopressor therapy in one patient. The only apparent proarrhythmic effect consisted of an isolated change in the morphology of the VT, that resolved spontaneously on withdrawal of the drug. No mortality occurred at the hospital. CONCLUSION: With appropriate rules for its administration, intravenous cibenzoline has the potential to become one of the first-line antiarrhythmic drugs, to be used for cardioversion of patients with spontaneous VT.