Electrophysiologic characteristics and results of radiofrequency catheter ablation in elderly patients with atrioventricular nodal reentrant tachycardia

Background

As in the general population, atrioventricular nodal reentrant tachycardia (AVNRT) is the most common regular supraventricular tachycardia in the elderly patients. We tried to compare electrophysiologic characteristics, efficacy, and risks of the radiofrequency (RF) catheter ablation of the slow pathway in elderly and young patients with AVNRT.

Methods

Between April 2001 and March 2005, 268 consecutive patients (190 females; mean age, 49 ± 14 years) with AVNRT underwent RF catheter ablation at our institution. The patients were categorized into 2 groups: group 1 consists of patients younger than 65 years (n = 156), and group 2 consists of patients 65 years or older (n = 112).

Results

Compared with the younger subgroup, elderly patients more often had structural heart disease (11.6% vs 2.5%, P = .004), but there were no statistically significant differences in sex and symptoms during tachycardia (all P > .05). AVNRT cycle length was significantly longer in group 2 than in group 1 patients (P = .005). Among the conduction intervals of tachycardia, only atrio-his interval was significantly longer in group 2 patients (P = .007). The ablation fluoroscopy time, RF pulse duration, target temperature, applied energy, and number of RF applications were comparable in the 2 groups (All P > .05). Risk of atrioventricular block, pericardial effusion, and vascular thrombosis were similar in both groups (All P > .05). During follow-up with duration of 14 months, similar rate of recurrence was observed in the 2 groups (P = .94).

Conclusions

In elderly patients, slow pathway ablation is as effective and safe as in younger patients. Therefore, when considering different treatment options in elderly patients, an increased risk of complications or lower efficacy should not be a factor in determining the best therapeutic approach.     

Effect of first ventricular tachycardia cycle length on rate of ventricular arrhythmia recurrence in patients with implantable cardioverter-defibrillator

Background

Some controversies exist regarding the proper treatment of hemodynamically tolerated and slow ventricular tachycardia (VT). We intended to assess the effect of cycle length of first VT episode on total ventricular arrhythmia burden in a cohort of patients with implantable cardioverter-defibrillator (ICD).

Method

Between March 2000 and March 2005, 195 patients underwent ICD implantation at our center. We included 158 patients (mean age, 58.3 ± 12.9 years) with follow-up of 3 months or more in this study. Clinical, electrocardiographic, and ICD-stored data and electrograms were collected and analyzed.

Results

During the follow-up of 16.7 ± 10.6 months, 45 (28.5%) and 20 (12.6%) patients received first appropriate ICD therapy for VT and ventricular fibrillation, respectively. We divided the 45 patients with VT (based on the median value of VT cycle length) into 2 groups. Although patients with VT cycle length of less than 350 had higher total mean number of appropriate ICD therapy (25 vs 6.3, P = .023), during multivariate regression analysis, only left ventricular ejection fraction (EF) of less than 25% (P = .020) was correlated with total number of appropriate ICD therapy. First VT cycle length (P = .341), QRS duration (P = .126), age (P = .405), underlying heart disease (P = .310), indication of ICD implantation (P = .113), and sex (P = .886) have failed to predict the total burden of ventricular arrhythmia during the follow-up period.

Conclusion

After adjustment for left ventricular EF, initial VT cycle length per se did not confer a lower risk for subsequent ventricular arrhythmia recurrence compared with those with faster VT. Left ventricular EF of less than 25% was correlated with higher ventricular arrhythmia burden in patients with ICD.     

Are wide complex tachycardia algorithms applicable in children and patients with congenital heart disease?

Introduction

Several algorithms have been developed to help determine the etiology of wide complex tachycardias (WCTs) in adults. Sensitivity and specificity for differentiating supraventricular tachycardia (SVT) with aberration from ventricular tachycardia (VT) in adults have been demonstrated to be as high as 98% and 97%. These algorithms have not been tested in the pediatric population. We hypothesize that these algorithms have lower diagnostic accuracy in children and patients with congenital heart disease.

Methods

A retrospective review of the pediatric electrophysiology database at Stanford from 2001 to 2008 was performed. All children with WCT, a 12-lead electrocardiogram (ECG) available for review, and an electrophysiology study confirming the etiology of the rhythm were included. Patients with a paced rhythm were excluded. The ECGs were analyzed by 2 electrophysiologists blinded to the diagnosis according to the algorithms described in Brugada et al,² and Vereckei et al.⁵ Additional ECG findings were recorded by each electrophysiologist.

Results

A total of 65 WCT ECGs in 58 patients were identified. Supraventricular tachycardia was noted in 62% (40/65) and VT in 38% (25/65) of the ECGs. The mean age was 13.5 years (SD ± 5.1), the mean weight was 51.8 kg (SD ± 22.4), and 48% (31/65) were male. The mean tachycardia cycle length was 340 milliseconds (SD ± 95). Congenital heart disease (CHD) was present in 37% (24/65) of patients (7 tetralogy of Fallot, 6 Ebstein's, 4 double-outlet right ventricle, 3 complex CHD, 2 d-transposition of great arteries, 1 status-post orthotopic heart transplantation, 1 ventricular septal defect). The Brugada algorithm correctly predicted the diagnosis 69% (45/65) of the time, the Vereckei algorithm correctly predicted the diagnosis 66% (43/65) of the time, and the blinded reviewer correctly predicted the diagnosis 78% (51/65) of the time. There was no difference in the efficacy of the algorithms in patients with CHD vs those with structurally normal hearts. The findings of left superior axis deviation (P < .01) and a notch in the QRS downstroke of V₁ or V₂ (P < .01) were more common in VT than SVT, whereas a positive QRS deflection in V₁ (P = .03) was more commonly present in SVT than VT.

Conclusion

The Brugada and Vereckei algorithms have lower diagnostic accuracy in the pediatric population and in patients with congenital heart disease than in the adult population. Left superior axis deviation and a notch in the QRS downstroke were more commonly associated with VT, whereas a positive QRS deflection in V₁ was more commonly associated with SVT in this population.     

Characterization and incidence of inducible monomorphic ventricular tachycardia in a postinfarction rabbit model

Objective

Ventricular tachycardia (VT), occurring late after myocardial infarction, is an important cause of sudden death. Animal models are useful for the investigation of this arrhythmia. The aim of this study is to develop and characterize a model of late postinfarction monomorphic VT in the rabbit.

Methods and Results

Myocardial infarction was created by ligation of the left circumflex artery. Cardiac electrophysiologic studies were performed 10 to 17 days postinfarction in 39 rabbits, in 10 sham-operated rabbits, and 6 control rabbits. Ventricular tachycardia was defined as a broad-complex tachycardia with a cycle length of more than 100 milliseconds, a duration of more than 10 seconds, and monomorphic QRS complexes. Using programmed stimulation, we induced VT in 9 rabbits (23%) in the infarct group but in none of the sham or control animals. The mean infarct size was 23% ± 9% (mean ± SD) of the left ventricle.

Conclusion

Coronary ligation in the rabbit creates a substrate, which allows the induction of sustained monomorphic VT with programmed stimulation. Monomorphic VT is not inducible in rabbits without myocardial infarction. This model might allow the testing of interventions that reduce the incidence of VT late after myocardial infarction.     

A new criterion to differentiate atrioventricular nodal reentrant tachycardia from atrioventricular reciprocating tachycardia: Combined AVR criterion

Aim

A combined aVR criterion is described as the presence of a pseudo r′ wave in aVR during tachycardia in patients without r′ wave in aVR in sinus rhythm and/or a ≥50% increase in r′ wave amplitude compared to sinus rhythm in patients with r′ wave in the basal aVR lead. We aimed to investigate the use of combined aVR criterion in differential diagnosis of atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reciprocating tachycardia (AVRT).

fQRS as a marker of granulomatous disease in patients presenting with ventricular tachycardia and normal left ventricular ejection fraction

Background

Granulomatous myocarditis may present with sustained monomorphic ventricular tachycardia (SMVT) in the presence of normal left ventricular ejection fraction (LVEF), and could be mistaken for idiopathic ventricular tachycardia (IVT). The use of cardiac imaging for diagnosis can be limited by availability and high cost. ECG is readily available and inexpensive. Fragmented QRS (fQRS) on ECG has been found to be associated with myocardial scar. We hypothesized that fQRS could be useful in the diagnosis of granulomatous VT (GVT).

Methods

We compared the 12-lead ECG of 16 patients with GVT and 42 patients with IVT who presented with SMVT.

Results

The presence of fQRS was significantly higher in the GVT group compared to the IVT group (75% versus 19.1%, p < 0.001). The location of fQRS correlated with delayed enhancement cardiac magnetic resonance imaging (DE-CMR) in the same segment in 4/16 patients in the GVT group. It correlated with an affected segment on either DE-CMR or 18FDG positron emission computed tomography in 4/11 patients in the GVT group who had both imaging modality. Whenever fQRS was present in contiguous leads other than the inferior leads, it always corresponded to an affected segment on imaging.

Conclusions

In patients presenting with SMVT and no structural heart disease, the presence of fQRS is strongly associated with granulomatous myocarditis. fQRS on the surface ECG is a helpful tool the presence of which should prompt a CMR for a definitive diagnosis.     

Radiofrequency Modification for Inducible and Suspected Pediatric Atrioventricular Nodal Reentry Tachycardia

Introduction: AV Node Reentry Tachycardia (AVNRT) is the second most common supraventricular tachycardia (SVT) undergoing pediatric radiofrequency ablation behind accessory pathway reentry tachycardias. AVNRT can be difficult to induce during electrophysiology study (EPS) and dual atrioventricular nodal (AVN) pathways physiology may not be demonstrated in young patients.Purpose: This report is the largest single center long term pediatric experience of radiofrequency modification of slow AVN input fibers for inducible or suspected (non-inducible) AVNRT.Results: One hundred thirty-two patients underwent slow input AVN modification from 1993 to 2002. The mean patient age was 13.7 years (4–20 yrs) with 62M/70F. Outpatient tachycardia was documented by ambulatory monitoring in all patients. AVNRT was induced in 98/132 patients during EPS (group A) with mean SVT cycle length of 324 msec (230–570 msec). Initial AVN modification (group A) was successful in 97/98 patients (99%). During 34/132 EPS, AVNRT was non-inducible; dual AVN physiology was present in 19/34 (group B), and 15/34 did not show evidence for dual AVN physiology (group C). These 34 patients underwent empiric AVN modification following discussion with patients’ families. Freedom of recurrence from SVT at 1 year was 96% for group A (94/98), 89% (17/19) for group B and 93% (14/15) for group C. 1 major and 6 minor complications occurred.Conclusions: AVN modification for AVNRT can be performed safely and effectively in pediatric patients with good long-term results. Empiric slow pathway AVN modification for non-inducible SVT results in a high rate of freedom from recurrence of tachycardia.     

Syncope and bundle branch block. Diagnostic yield of a stepped use of electrophysiology study and implantable loop recorders

Introduction and objectives

The objective of this study was to determine the diagnostic yield of a stepped protocol involving an electrophysiologic study (EPS) and implantable loop recorders (ILR) in patients with syncope and bundle branch block (BBB).

Methods

Eighty-five consecutive patients referred for syncope and BBB after initial non-diagnostic assessment underwent EPS including a pharmacological challenge with procainamide. Those patients without indication for defibrillator implantation received ILRs. Follow-up continued until diagnosis or end of battery life.

Results

The EPS was diagnostic in 36 patients (42%). The most frequent diagnoses were paroxysmal atrioventricular block (AVB) (n = 27), followed by ventricular tachycardia (VT) (n = 6). All patients with VT had structural heart disease; left BBB was more prevalent in this group. Thirty-eight patients received ILRs and diagnosis was achieved in 13 (34%) of them; paroxysmal AVB (n = 10) was the most frequent diagnosis. Median follow-up to diagnosis of paroxysmal AVB was 97 days (interquartile range 60-117 days). Paroxysmal AVB was more frequent in patients with right BBB and prolonged PR interval and/or axis deviation. We found no occurrence of VT or arrhythmic death during follow-up.

Conclusions

The most common etiology of syncope in patients with BBB was paroxysmal AVB, followed by VT. The stepped use of EPS and ILR in negative patients enables us to safely achieve a high diagnostic yield, given that VT is usually diagnosed during EPS.Full English text available from: www.revespcardiol.org     

Orthostatic Syndromes Differ in Syncope Frequency

Background

There are conflicting opinions on whether postural tachycardia syndrome predisposes to syncope. We investigated this relationship by comparing the frequency of syncope in postural tachycardia syndrome and orthostatic hypotension.

Methods

We queried our autonomic laboratory database of 3700 patients. Orthostatic hypotension and postural tachycardia syndrome were defined in standard fashion, except that postural tachycardia syndrome required the presence of orthostatic symptoms and a further increase in heart rate beyond 10 minutes. Syncope was defined as an abrupt decrease in blood pressure and often, heart rate, requiring termination of the tilt study. Statistical analysis utilized Fisher's exact test and Student's t test, as appropriate.

Results

Of 810 patients referred for postural tachycardia syndrome, 185 met criteria while another 328 patients had orthostatic hypotension. Of the postural tachycardia syndrome patients, 38% had syncope on head-up tilt, compared with only 22% of those with orthostatic hypotension (P <.0001). In the postural tachycardia group, syncope on head-up tilt was associated with a clinical history of syncope in 90%, whereas absence of syncope on head-up tilt was associated with a clinical history of syncope in 30% (P <.0001). In contrast, syncope on head-up tilt did not bear any relationship to clinical history of syncope in the orthostatic hypotension group (41% vs 36%; P = .49).

Conclusion

Our results demonstrate that syncope (both tilt table and clinical) occurs far more commonly in patients who have postural tachycardia syndrome than in patients with orthostatic hypotension. These findings suggest that one should be clinically aware of the high risk of syncope in patients with postural tachycardia syndrome, and the low-pressure baroreceptor system that is implicated in postural tachycardia syndrome might confer more sensitivity to syncope than the high pressure system implicated in orthostatic hypotension.     

Failure in short-term prediction of ventricular tachycardia and ventricular fibrillation from continuous electrocardiogram in intensive care unit patients

Background

Patients in the intensive care unit (ICU) setting are prone to malignant ventricular arrhythmias. We sought to test whether electrocardiographic (ECG) markers of autonomic tone, ventricular irritability, and repolarization lability could be used in short-term prediction of ventricular arrhythmias in this patient population.

Methods

We studied 38 patients with sustained (>30 seconds) monomorphic ventricular tachycardia, polymorphic ventricular tachycardia, or ventricular fibrillation while monitored in the ICU and 30 patients without arrhythmia in the ICU who served as controls. All patients had at least 12 hours of continuously recorded multilead ECG before arrhythmic event. Mean heart rate and measures of heart rate variability, QT variability, and ventricular ectopy were quantified in 1-hour epochs for the 12 hours before the arrhythmic event and in 5-minute epochs for the last hour preevent (and using a random termination time point in controls).

Results

A modest downward trend in QT variability and a rise in heart rate were observed hours before polymorphic ventricular tachycardia and ventricular fibrillation events, although no significant changes heralded monomorphic ventricular tachycardia and no changes in any parameter predicted imminent ventricular arrhythmia of any type. There were no significant differences in ECG parameters between arrhythmia patients and controls.

Conclusions

In ICU patients, sustained ventricular arrhythmias are not preceded by change in ECG measures of autonomic tone, repolarization variability, and ventricular ectopy. Short-term arrhythmia prediction may be difficult or impossible in this patient population based on ECG measures alone.     

Ablation of left atrial tachycardia with cycle length alternans after atrial fibrillation ablation: significance of fractionated electrogram mapping

Introduction

Atrial tachycardia (AT) with cycle length alternans occurring after atrial fibrillation ablation has not been previously described.

Methods

Among 66 patients with left AT, stable AT with 2 alternating cycles was registered in 5 cases. Activation mapping of both alternating cycles was performed in all 5 patients. Entrainment and fractionated electrogram mappings were also carried out.

Results

Among 10 AT cycles, activation maps suggested underlying mechanism of 5 cycles (50%) in 3 patients. Entrainment pacing was helpful in 2 patients (confirmed mechanism of 2 AT cycles). Catheter ablation successfully terminated AT in all 5 patients: ablation of sites with fractionated potentials in 4 patients and mitral isthmus ablation in 1 patient.

Conclusion

Consecutive activation mapping of both AT cycles is feasible for mechanism determination in some patients. The results of our small study suggest that fractionated electrogram-guided ablation might be a reasonable approach for termination of this type of AT.     

Troponin elevation in supraventricular tachycardia: primary dependence on heart rate

Background

It is known that some patients with supraventricular tachycardia (SVT) could have increased troponin levels without coronary artery disease.

Objectives

To compare the cardiovascular risk of patients admitted with SVT with troponin T elevation (T+ patients) versus those without (T- patients), to determine if the rise in troponin levels could be predicted, and to identify the right approach in T+ patients.

Methods

Retrospective database search of patients with SVT from 2002 to 2007 either with or without troponin T elevation at admission.

Results

Of the 73 study patients, there were 24 (32.9%) T+ patients and 49 (67.1%) T- patients. All except 5 T+ patients underwent either a stress test/MIBI or a coronary angiogram. Two noninvasive tests were positive and only 1 patient needed an angiogram and percutaneous coronary intervention; none of the other angiograms triggered any further treatment. Of the 49 T- patients, 11 had a noninvasive stress test; none of these tests was positive or triggered any further treatment. Compared with that of T- patients, the maximum heart rate was significantly higher in T+ patients (190.8 versus 170.3 beats per minute, P = .008). A correlation was found between the maximal heart rate during SVT and the level of troponin elevation (r = 0.637, P = .001).

Conclusions

SVT could be associated with a troponin elevation without any severe coronary artery disease. In most patients, either conservative management or noninvasive stratification seems to be sufficient; an invasive strategy could then be reserved only for high-risk patients who tested positive. The only clinical variable correlated with the troponin rise was a higher maximal heart rate during the SVT episode.     

Early sustained ventricular arrhythmias complicating acute myocardial infarction

Objective

Sustained ventricular arrhythmias complicate 2% to 20% of acute myocardial infarctions (MIs) and are associated with increased in-hospital mortality. However, it remains unclear whether successful mechanical revascularization improves outcomes in these patients. The objective of this analysis was to identify predictors of sustained ventricular arrhythmias after acute MI and to determine the influence of successful revascularization on in-hospital mortality.

Methods

We conducted a retrospective cohort study of all patients who underwent percutaneous coronary intervention for acute MI in New York State between 1997 and 1999.

Results

Of the 9015 patients who underwent percutaneous coronary intervention for acute MI, 472 (5.2%) developed sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) before revascularization. After multivariable adjustment, independent predictors of sustained VT/VF included cardiogenic shock (odds ratio [OR], 4.10; 95% confidence interval [CI], 3.20-5.58; P <.001), heart failure (OR, 2.86; 95% CI, 2.24-3.67: P <.001), chronic kidney disease (OR, 2.58; 95% CI, 1.27-5.23; P = .009), and presentation within 6 hours of symptom onset (OR, 1.46; 95% CI, 1.18-1.81; P = .001). Patients with sustained VT/VF had greater in-hospital mortality (16.3% vs 3.7%, P <.001). Although successful percutaneous coronary intervention was associated with decreased in-hospital mortality in patients with VT/VF (P <.001), patients with sustained VT/VF and successful revascularization experienced increased mortality compared with patients without sustained ventricular arrhythmias (P <.001).

Conclusion

Among patients undergoing percutaneous coronary intervention for acute MI, sustained VT/VF remains a significant complication associated with a 4-fold increased risk of in-hospital mortality. Early mortality is reduced after successful percutaneous coronary intervention, but remains elevated in this high-risk group.     

Does instant coffee prevent acute liver injury induced by carbon tetrachloride (CCl4)?

Objective

To investigate the protective effect of instant coffee (IC) on acute liver injury induced by CCl₄.

Methods

The study included 32 rats which were allocated to four groups: control (n: 8), CCl₄ (n: 8), CCl₄ + IC (n: 8) and IC (n: 8). Malondialdehyde, which is a lipid peroxidation product, and levels of antioxidant capacity were measured and histopathological data were compared.

Results

It was seen in the study that lipid peroxidation products that increased in the plasma and liver tissue of the CCl₄ group decreased by IC administration. There was an increase in the measured antioxidant parameters, which were total antioxidant capacity (TAOC), sulphydryl (SH) and ceruloplasmin levels. Histopathologically, it was found that inflammation and necrosis which increased in the group administered CCl₄ decreased significantly with IC administration, but there steatosis did not change.

Conclusions

It was seen that IC had a protective role in acute liver injury induced by CCl₄, but did not affect steatosis.     

The relationship between visfatin and HOMA-IR in hypertensive patients, and the effect of antihypertensive drugs on visfatin and HOMA-IR in hypertensive patients with insulin resistance

Objective

To investigate the correlation between serum visfatin and insulin resistance (IR) in non-diabetic essential hypertensive (EH) patients with and without IR, and to evaluate the effect of antihypertensive treatment on serum visfatin and IR in these patients.

Methods

A total of 81 non-diabetic EH patients, including 54 with IR and 27 without IR, were enrolled. After two weeks wash-out, patients with IR were randomly assigned to telmisartan (group T) or amlodipine (group A) for 6 months. Blood samples were taken before and after treatment for measurement of routine biochemical parameters, visfatin and insulin resistance (measured by HOMA-IR).

Results

Visfatin was independently correlated with HOMA-IR (r = 0.845, P = 0.000). After 6 months of treatment, both drugs lowered HOMA-IR, more significantly so in group T than group A (P = 0.010). Serum visfatin levels increased in group T but decreased in group A.

Conclusion

Serum visfatin levels were higher in non-diabetic EH patients with IR compared with those without IR. Visfatin is independently correlated with HOMA-IR. Telmisartan lowers HOMA-IR to a greater extent than amlodipine. Interestingly, serum visfatin increased with telmisartan yet decreased with amlodipine treatment.     

A simple algorithm for defining the mechanism and the chamber of origin in atrial tachycardias

Introduction

Although macroreentrant atrial tachycardia (MRAT) and focal atrial tachycardia (FAT) can be successfully cured by catheter ablation, the proper diagnosis and treatment of these arrhythmias can still be challenging.

Aim

The objective of this study is to develop an algorithm allowing rapid diagnosis of the mechanism and the chamber of origin of atrial tachycardia based on intracardiac catheter recordings from the right atrium and the coronary sinus (CS).

Methods

A 2-stepped algorithm was designed: (1) The time of biatrial activation expressed as a percentage of the tachycardia cycle length served to discriminate FAT from MRAT. (2) In FAT, the direction of activation of the CS catheter and the earliest atrial activation were used to define the chamber of origin. In MRAT, the time of right atrium activation was determined or entrainment was used at different sites. Thirty-two intracardiac recordings were reviewed off-line after the algorithm by 4 electrophysiologists blinded to the mechanism and the chamber of origin. The results of their analysis were compared with the intraoperative diagnosis.

Results

The algorithm correctly identified 11 (100%) of 11 FATs and 19 (90.4%) of 21 MRATs. The site of origin was correctly identified in 8 (72.7%) of 11 FATs and in 20 of 21 (95.2%) MRATs. The site of origin was misidentified in 3 FATs, all arising from the CS ostium.

Conclusions

This algorithm allows rapid discrimination between FAT and MRAT. The chamber of origin is detected with a high accuracy in MRAT. However, the earliest atrial activation taken as an isolated event is not a good predictor for the chamber of origin in FAT arising from the ostium of the CS.     

Heart rate turbulence and other autonomic risk markers for arrhythmia risk stratification in dilated cardiomyopathy

Background

Noninvasive arrhythmia risk stratification in patients with nonischemic dilated cardiomyopathy (DCM) using autonomic markers have yielded disappointing results. Heart rate turbulence is a new method to assess cardiac autonomic function.

Aim

The aim of the study was to compare the predictive value of heart rate turbulence with those of conventional autonomic risk markers for ventricular tachyarrhythmic events in patients with DCM.

Methods

The predictive value of heart rate turbulence, baroreflex sensitivity (phenylephrine method), and heart rate variability was assessed in patients with symptomatic congestive heart failure due to DCM who were in sinus rhythm and had a 24-hour Holter recording. Patients were followed for a combined end point of ventricular tachyarrhythmic events.

Results

A total of 114 patients (mean left ventricular ejection fraction, 28 ± 11%), included in the Frankfurt DCM database between 1996 and 2000, fulfilled the criteria for inclusion in this study. Determinate test results were obtained for heart rate variability in 98%, for baroreflex sensitivity in 90%, and for heart rate turbulence in 75% of patients (P = .008). Correlation between the different autonomic markers were only modest (r values, 0.36-0.43). During a follow-up of 22 ± 17 months, an end point event occurred in 15 patients. On univariate analysis, left ventricular ejection fraction and baroreflex sensitivity were significant predictors of arrhythmic events. On multivariate analysis, only baroreflex sensitivity remained an independent predictor (χ² = 3.17; P = .07).

Conclusion

Reliable analysis of heart rate turbulence is possible in approximately 75% of eligible patients with DCM. Whereas blunted baroreflex sensitivity is a predictor of arrhythmic events, heart rate variability and turbulence do not yield predictive power in these patients.     

Prevention of Plasmodium vivax malaria recurrence: Efficacy of the standard total dose of primaquine administered over 3 days

Background

The standard total dose (STD) of primaquine to prevent Plasmodium vivax recurrence is 0.25 mg/kg day administered over 14 days (STD-14). We evaluated, in an endemic zone of Colombia, the anti-recurrence efficacy of the STD dose administered over 3 and 14 days, and of sub-STD dose administered over 3 days (71%STD-3, 50%STD-3).

Methods

A controlled clinical trial was carried out with 188 subjects allocated into one of four treatment groups: STD-14, STD-3, 71%STD-3, 50%STD-3.

Results

Recurrences during the 120 days of follow-up were 15% in STD-14, and 57% in STD-3. Treatment with 71%STD-3 and 50%STD-3 resulted in recurrence in >48% subjects within 120 days after the primary episode. High daily doses (1.17 mg/kg day) were well tolerated.

Conclusions

(a) The standard dose and regimen (STD-14) of primaquine to prevent P. vivax relapse is recommended. The administration of the same dose over 3 days (STD-3) should be avoided; (b) doses lower than the STD doses administered over 3 days are ineffective in preventing relapse.     

C-reactive protein elevation independently influences the procedural success of percutaneous balloon mitral valve commissurotomy

Background

Markers of systemic inflammation including C-reactive protein (CRP) appear to predict morbidity and mortality in various clinical conditions. The presence of systemic inflammation and its impact on the procedural success of percutaneous balloon mitral valve commissurotomy (PBMC) in patients with rheumatic mitral stenosis has not been previously demonstrated.

Methods

Measurements of CRP with a high-sensitivity assay were performed at the time of PBMC or during post-procedural follow-up in 119 patients with mitral stenosis of rheumatic morphology. Patients were questioned to exclude confounders of CRP elevation and categorized into undetectable (≤0.10 mg/L) and detectable (>0.10 mg/L) CRP levels. Detectable levels were further classified into assay range (>0.10 and ≤6.0 mg/L) and elevated (>6.0 mg/L).

Results

CRP was detectable in 76% of patients and elevated (>6.0 mg/L) in 36% of patients studied. Procedural success occurred in 89% of patients with undetectable CRP, as compared with only 67% in patients with detectable CRP (P = .028). This effect remained after controlling for age and valve score (previously described predictors of PBMC success).

Conclusions

Systemic inflammation is common in patients with rheumatic mitral valve stenosis, and the relationship between procedural success and CRP suggests persistent inflammation may affect the results of PBMC.     

Differences in care-seeking behavior for acute chest pain in the United States and Japan

Background

Delay from onset of acute myocardial infarction symptoms to the delivery of medical care is a major determinant of prognosis. Although studies have explored patient factors for delay in seeking care, there are limited data on international differences in care-seeking behavior.

Methods

We surveyed 1032 people in the United States and 1422 people in Japan in January 1997 on decision-making responses to a chest pain scenario representing acute MI. Participants were asked about how they would seek initial care and how promptly they would seek care.

Results

The mean age was 43.6 years in the United States and 48.3 years in Japan. For the hypothetical scenario, US respondents were more likely to seek care at an emergency department (22.9% vs 16.2% in Japan) or through emergency medical services/911 (55.9% vs 32.9% in Japan, P = .001). American subjects were also more likely to seek care immediately (83.1% vs 56.4% in Japan, P = .001).

Conclusion

Respondents in the United States and Japan differed substantially in their responses to a hypothetical chest pain scenario. Whether these differences result from cultural or health care system factors and whether these apparent attitudes produce gaps in real responses to acute coronary syndromes must be explored in further studies.