Cost effectiveness of cardiac resynchronization therapy in the Nordic region: an analysis based on the CARE-HF trial.

BACKGROUND: The aim of this study was to investigate the cost-effectiveness of cardiac resynchronization therapy (CRT) in Denmark, Finland and Sweden. The analysis was based on the CARE-HF trial, a randomised clinical trial investigating the efficacy of adding CRT (n=409) to optimal pharmacological treatment (n=404) in patients with moderate to severe heart failure with markers of cardiac dyssynchrony. The average follow-up time was 29.4 months. METHODS: The health effects were measured in terms of quality-adjusted life years (QALYs) gained. Data on health care resource consumption from CARE-HF was combined with costs for CRT implantation and hospitalisation from university hospitals in Denmark, Finland and Sweden. Calculations were based on patients' expected life time. The expected device lifetime (6 years) was used for CRT, and no additional gains in clinical effects were assumed after the 6 years. RESULTS: The cost-effectiveness ratio per QALY gained was 4800 euros in Denmark, 3600 euros in Finland and 6700 euros in Sweden. The 95% confidence intervals for the cost per QALY gained varied between a lower limit of 1169 euros in Finland to an upper limit of 17,482 euros in Sweden. These values were all below the threshold for being cost-effective in Denmark, Finland and Sweden. CONCLUSIONS: The study indicates that CRT is a cost-effective treatment in Scandinavian health care settings compared to traditional pharmacological therapy and can therefore be recommended for routine use in patients with moderate to severe heart failure and markers of dyssynchrony.

Thoracic epidural anesthesia does not influence the occurrence of postoperative sustained atrial fibrillation.

BACKGROUND: To evaluate whether thoracic epidural anesthesia (TEA) can reduce the incidence of atrial fibrillation (AF) after coronary artery bypass grafting (CABG). METHODS: Forty-one patients undergoing CABG were treated with TEA intraoperatively and postoperatively. Another 80 patients served as the control group. The sympathetic and parasympathetic activities were evaluated by analysis of neuropeptides, catecholamines and heart rate variability (HRV), preoperatively and postoperatively. RESULTS: Postoperative AF occurred in 31.7% of the TEA-treated patients and in 36.3% of the untreated patients (p = 0.77). TEA significantly suppressed sympathetic activity, as indicated by a less pronounced increase of norepinephrine and epinephrine (p = 0.03, p = 0.02) and a significant decrease of neuropeptide Y (p = 0.01) postoperatively in TEA-treated patients compared to untreated patients. The HRV variable expressing sympathetic activity was significantly lower and the postoperative increase in heart rate was significantly less in the TEA group than in the control group after surgery (p = 0.01, p < 0.001). Among patients developing AF, the maximal number of supraventricular premature beats per minute increased significantly in untreated patients postoperatively but remained unchanged in TEA-treated patients (p = 0.004 versus p = 0.86). CONCLUSIONS: TEA has no effect on the incidence of postoperative sustained AF, despite a significant reduction in sympathetic activity.

Diminished circadian variation in heart rate variability before surgery in patients developing postoperative atrial fibrillation.

OBJECTIVE: To evaluate the role of the autonomic nervous system for the development of atrial fibrillation (AF) after coronary artery bypass surgery. DESIGN: Eighty patients without a previous history of AF were included. The sympathetic and parasympathetic activity were evaluated by the analysis of heart rate variability (HRV) in the frequency domain from 24-h Holter recordings and by measuring neuropeptides (neuropeptide Y, chromogranin A, chromogranin B, and pancreatic polypeptide (PP)) and catecholamines, obtained pre- and postoperatively. RESULTS: Preoperatively, patients (36.3%) developing AF postoperatively showed a statistically significant less circadian variation in the HRV variables, the high-frequency (HF) component (p = 0.013) and the low-frequency (LF)/HF ratio (p = 0.007), than patients remaining in sinus rhythm. The HF component and PP. both reflecting parasympathetic activity, and all other variables in the frequency domain, decreased significantly after surgery in both patient groups (p < 0.0001). Although catecholamines increased significantly postoperatively in both patient groups, neither catecholamines nor neuropeptides expressing sympathetic activity, differed between the two groups. PP was, however, significantly higher in patients with postoperative AF than in those with sinus rhythm postoperatively on day 1. CONCLUSION: The diminished circadian variation in HRV before surgery and the indirect signs of a higher parasympathetic activity in patients developing postoperative AF compared with patients remaining in sinus rhythm, may indicate a propensity for AF.

Effects of the maze operation on health-related quality of life in patients with atrial fibrillation.

BACKGROUND: Maze surgery for atrial fibrillation (AF) is a curative therapy, but its effect on health-related quality of life has not been studied. METHODS AND RESULTS: Maze operations were performed in 48 patients with drug-refractory AF. The majority of patients (80%) had lone AF, and the primary indication for surgery in all patients was AF. The SF-36 Health Survey was used to assess quality of life before operation and at 6 months and 1 year after surgery. Twenty-five patients were available for the 1-year follow-up and completed all questionnaires. Before maze surgery, the SF-36 scores were significantly lower than in the general Swedish population, reflecting significant impairment in well-being, physical and social functioning, and mental health. After maze surgery, the quality of life was significantly improved at 6 months and at 1 year on all scales except for bodily pain, which, however, was not significantly decreased before surgery. At both 6 months and 1 year after maze surgery, quality of life, measured by the SF-36, reached the levels of the general Swedish population. CONCLUSIONS: The maze operation can significantly improve the health-related quality of life in selected groups of patients with both paroxysmal and chronic AF refractory to antiarrhythmic therapy.

Tachyarrhythmias and triggering factors for atrial fibrillation after coronary artery bypass operations.

BACKGROUND: We evaluated the role of supraventricular arrhythmias and assessed clinical predictors of atrial fibrillation (AF) that developed after coronary artery bypass operations. METHODS: Eighty patients, with a mean age of 65.8 years, underwent 24-hour Holter monitoring preoperatively and for 4 consecutive days postoperatively, or until clinically documented AF, for analysis of the number of premature beats and tachyarrhythmias. Atrial areas and atrial peptides were measured preoperatively and postoperatively. RESULTS: Twenty-nine of 80 (36.3%) patients had postoperative AF. Preoperatively, the maximal supraventricular premature beats per minute were higher in the AF group (p = 0.02). The body mass index and total amount of cardioplegia were lower (p = 0.02 and p = 0.006, respectively), and withdrawal of beta-blockers postoperatively more frequent (p = 0.001) in the AF group, but atrial areas and atrial peptides did not differ. CONCLUSIONS: Frequent supraventricular premature beats preoperatively may indicate a propensity for AF. A larger amount of cardioplegia during the cross-clamp period may reduce the risk of postoperative AF. Further studies are mandatory to clarify why patients with lower body mass index were more prone to AF.

The sensitivity of transesophageal pacing for screening in atrial tachycardias.

Transesophageal atrial pacing and recording performed in 128 patients for palpitations or tachycardia was retrospectively evaluated and compared to the same procedure in 77 routinely evaluated patients after a catheter ablation procedure. The sensitivity and specificity of the described protocol was 74 and 90% respectively. The procedure was well tolerated and a majority of patients could be completely evaluated according to the protocol. The outcome of the first time investigation influenced the subsequent choice of therapy in the studied population. The results suggest that transesophageal pacing is a valuable tool for evaluation of atrial tachycardias with specificity, sensitivity and tolerability comparable to other noninvasive methods used in cardiology.

Comparison of QT dispersion during atrial fibrillation and sinus rhythm in the same patients, at normal and prolonged ventricular repolarization.

AIMS: Drug-induced increase in QT dispersion has been associated with increased risk of ventricular proarrhythmia. The aim of the present study was to compare QT dispersion during atrial fibrillation and sinus rhythm in the same patients at normal and prolonged ventricular repolarization. METHODS AND RESULTS: Sixty-one patients who had had chronic atrial fibrillation for 8 +/- 14 months received a 6 h infusion of the Ikr-blocker almokalant, the first 90 min of which are used for this analysis. The following day, after conversion to sinus rhythm, by almokalant (n = 19) or direct current cardioversion (n=42), an identical 90 min infusion was administered. Prior to infusion, there was no difference in precordial QT dispersion between atrial fibrillation and sinus rhythm (29 +/- 12 vs 36 +/- 17 ms, P=ns). During infusion, at prolonged repolarization, the increase in QT dispersion was greater during sinus rhythm than during atrial fibrillation (58 +/- 49 vs 30 +/- 15 ms, P=0.0011, after 30 min infusion). No correlation was found between QT dispersion and the QT or RR interval. CONCLUSION: QT dispersion during atrial fibrillation does not differ from QT dispersion during sinus rhythm during normal repolarization. while measurement of QT dispersion during prolonged repolarization, induced by an Ikr-blocker, yielded larger values during sinus rhythm than during atrial fibrillation.

Effects of the Ikr-blocker almokalant and predictors of conversion of chronic atrial tachyarrhythmias to sinus rhythm. A prospective study.

PURPOSE: To assess the efficacy of the Ikr-blocker almokalant attempting to convert chronic atrial tachyarrhythmias, and to find predictors of conversion, to sinus rhythm. METHODS: The electrophysiological effects of a 6-hour infusion of almokalant, to a total dose of 25 +/- 4 mg, were assessed by ECG and transesophageal atrial electrograms (TAE) in 100 consecutive patients with atrial fibrillation/flutter (n = 95/5) of 8 +/- 12 months' duration (range 1 to 99 months). RESULTS: The conversion rate was 32%. The time to conversion was 3.5 +/- 2.2 hours. During infusion increases in QTtop (292 +/- 35 to 335 +/- 44 ms, p < 0.001, after 30 minutes), QT (387 +/- 40 to 446 +/- 60 ms, p < 0.001), corrected QT (425 +/- 30 to 487 +/- 44 ms, p < 0.001), and QT dispersion (21 +/- 12 to 29 +/- 31 ms, p = 0.02), were paralleled by decreases in T wave amplitude (0.31 +/- 0.19 to 0.23 +/- 0.16 mV, p < 0.001), and atrial rate (425 +/- 78 to 284 +/- 44 beats per minute (bpm) on ECG, and 396 +/- 72 to 309 +/- 44 bpm on TAE), with no differences between converters to sinus rhythm and non-converters. Patients with aberrantly conducted beats, and T wave variation, also increased. Calcium antagonists were more common among converters. A decreasing T wave amplitude predicted conversion. Four patients developed torsades de pointes. CONCLUSIONS: This study demonstrates class III action of almokalant, with a conversion rate of 32% of long-standing, chronic atrial tachyarrhytmias. An early decrease in T wave amplitude was associated with conversion to sinus rhythm.

Electrocardiographic and clinical predictors of torsades de pointes induced by almokalant infusion in patients with chronic atrial fibrillation or flutter: a prospective study.

The aim of this study was to identify predictors of torsades de pointes (TdP) in patients with atrial fibrillation (AF) or flutter exposed to the Class III antiarrhythmic drug almokalant. TdP can be caused by drugs that prolong myocardial repolarization. One hundred patients received almokalant infusion during AF (infusion 1) and 62 of the patients during sinus rhythm (SR) on the following day (infusion 2). Thirty-two patients converted to SR. Six patients developed TdP. During AF, T wave alternans was more common prior to infusion (baseline) in patients developing TdP (50% vs 4%, P < 0.01). After 30 minutes of infusion 1, the TdP patients exhibited a longer QT interval (493 +/- 114 vs 443 +/- 54 ms [mean +/- SD], P < 0.01), a larger precordial QT dispersion (50 +/- 74 vs 27 +/- 26 ms, P < 0.05), and a lower T wave amplitude (0.12 +/- 0.21 vs 0.24 +/- 0.16 mV, P < 0.01). After 30 minutes of infusion 2, they exhibited a longer QT interval (672 +/- 26 vs 489 +/- 74 ms, P < 0.001), a larger QT dispersion in precordial (82 +/- 7 vs 54 +/- 52 ms, P < 0.01) and extremity leads (163 +/- 0 vs 40 +/- 34 ms, P < 0.001), and T wave alternans was more common (100% vs 0%, P < 0.001). Risk factors for development of TdP were at baseline: female gender, ventricular extrasystoles, and treatment with diuretics; and, after 30 minutes of infusion: sequential bilateral bundle branch block, ventricular extrasystoles in bigeminy, and a biphasic T wave. Patients developing TdP exhibited early during almokalant infusion a pronounced QT prolongation, increased QT dispersion, and marked morphological T wave changes.

Right atrial free wall conduction velocity and degree of anisotropy in patients with stable sinus rhythm studied during open heart surgery.

AIMS: Although the perpetuation of several supraventricular arrhythmias is critically dependent upon intra-atrial conduction, the literature lacks detailed information on normal values of conduction velocity and degree of anisotropy. In order to explore these factors further, we have measured conduction velocities at the right atrial free wall during sinus rhythm and during atrial pacing in four directions parallel and perpendicular to the atrioventricular groove in patients with normal atria and stable sinus rhythm. METHODS AND RESULTS: Using a Bard Cardiac Mapping System, atrial ECGs were recorded using a 3 x 4 cm electrode array with 56 equally spaced bipolar electrodes in 12 patients undergoing open heart surgery due to ischaemic heart disease or Wolf-Parkinson-White syndrome. A bipolar pen probe connected to a Medtronic 5328 stimulator was used for pacing at a 10% higher rate than sinus rhythm. The local activation times were manually set and isochronal activation maps were created for each recording. The conduction velocities were calculated from the activation maps over a distance ranging from 2.2 to 4.2 cm. The majority of the activation maps showed no signs of anisotropy; the others had less than 15% spatial inhomogeneity of conduction. Mean conduction velocity, calculated from five consecutive beats, was 88 +/- 9 cm.s-1 (mean +/- SD), ranging between 68 +/- 4 and 103 +/- 3 cm.s-1 during sinus rhythm. Mean conduction velocity during atrial pacing was 81 +/- 16 cm.s-1 at a propagation direction of 0 degree, 74 +/- 14 cm.s-1 at a 90 degrees direction, 79 +/- 12 cm.s-1 at 180 degrees and 78 +/- 20 cm.s-1 at 270 degrees, where 0 degree was parallel to the atrioventricular groove in the cranial direction and the angle increased counter-clockwise. Mean conduction velocity during sinus rhythm was significantly higher (P < 0.05) than during atrial pacing at the 90 degrees and 180 degrees directions but not compared to atrial pacing at 0 degree or 270 degrees. There was no significant difference in mean conduction velocity in different directions during atrial pacing. CONCLUSION: Although anisotropy was documented during conduction velocity in individual cases, conduction velocity was not dependent on propagation direction at the epicardial right atrial free wall in patients with stable sinus rhythm. These findings do not exclude the presence of internodal preferential pathways as these are located sub-epicardially and a marked transmural discordance in activation has previously been documented in the vicinity of such pathways.

Clinical value of transesophageal atrial stimulation and recording in patients with arrhythmia-related symptoms or documented supraventricular tachycardia--correlation to clinical history and invasive studies.

The main objective of the present study was to evaluate the clinical applicability of transesophageal atrial stimulation (TAS) and recording with regard to inducibility of supraventricular tachycardia (SVT) in patients with either an ECG-documented paroxysmal SVT or a clinical history of palpitations suggesting this disease. A further objective was to assess the inducibility of SVT and to compare the inducibility by TAS with that obtained by an invasive electrophysiologic study (EPS). A total of 64 patients (aged 13-74 years) with ECG-documented paroxysmal SVT (n = 50) or only a history of palpitations (n = 14) was referred for TAS. Preexcitation was present in 35 patients. The study protocol included single and double extrastimuli delivered at a basic paced interval of 500 ms, and incremental atrial stimulation until a cycle length of 275 ms or a second-degree AV block appeared. In 10 patients atropine intravenously was required for induction. The same protocol was used in 34 of the patients who also underwent invasive EPS. TAS was completed in 56 of 64 patients (88%). In this group SVT was induced during TAS in 84% (47/56). Of patients with ECG-documented tachycardia, clinical tachycardia was induced in 90% (35/39) with ECG-documented regular paroxysmal SVT and in 67% of patients (4/6) with ECG-documented atrial fibrillation. In patients without ECG-documented atrial fibrillation. In patients without ECG-documented tachycardia, clinically relevant arrhythmia was induced in 73% (8/11). In 30 of 32 patients (94%) with an inducible tachycardia during invasive EPS, it was also possible to induce the tachycardia by TAS.(ABSTRACT TRUNCATED AT 250 WORDS)

Epiglottitis and torsade de pointes tachycardia.

Severe throat infection is not usually associated with a higher risk of paroxysmal attacks of torsade de pointes tachycardia. A patient is reported in whom epiglottitis was associated with the sudden development of cardiac syncope caused by an acquired adrenergic-dependent long QT syndrome and the development of ventricular arrhythmias.

[The diagnostic value of esophageal ECG and transesophageal atrial stimulation in paroxysmal supraventricular tachycardia]. / Den diagnostiske vaerdi af esophagus-ekg og transøsofageal atrial stimulation ved paroksystisk supraventrikulaer takykardi.

Paroxysmal supraventricular tachycardia (PSVT) includes a group of common arrhythmias. The diagnosis should be based on 12-lead ECG. Oesophageal ECG, which registers mainly left-sided posterior atrial activity may be of value for further assessment of the arrhythmic mechanism in determination of the time relationship between atrial and ventricular signals. A ventriculoatrial interval during PSVT measured by oesophageal ECG of under 70 ms is evidence of atrioventricular nodal re-entry tachycardia while an interval of over 70 ms suggests orthodromic reciprocating tachycardia with participation of an accessory atrioventricular pathway. Transoesophageal atrial stimulation (TAS) via an electrode catheter is possible in approximately 90% of the patients with PSVT. TAS requires greater quantities of energy than endocardial stimulation and is associated with slight to moderate retrosternal discomfort. The method renders possible both programmed stimulation with the object of inducing arrhythmia and in stopping the majority of cases PSVT, with the exception of atrial fibrillation. The method is relatively simple, non-invasive, requires few resources and can be carried out on outpatients.

Localization of cardiac arrhythmias: conventional noninvasive methods.

Noninvasive localization of the accessory pathway (AP) in patients with the Wolff-Parkinson-White syndrome and of the site of origin of ventricular tachycardia (VT) is reviewed. 12-lead electrocardiography (ECG) is the most readily available method for localization of both the AP and the site of VT origin. Many published ECG criteria are introduced. The application of body surface potential mapping, vectorcardiography, nuclear phase imaging, echocardiography, computed tomography, nuclear magnetic resonance, and signal-averaged ECG in the localization of these arrhythmogenic substrates is also described. We believe that ECG is the most sensitive noninvasive method for AP localization as well as being convenient and simple; it may be used as the only noninvasive method for the initial evaluation. The left lateral AP, which occurs with an incidence of more than 40%, could be localized preoperatively by noninvasive methods only. For localization of the site of VT origin, none of the noninvasive methods is accurate enough for guiding the surgical and catheter-mediated ablative therapies so far.