Is ventricular repolarization heterogeneity a cause of serious ventricular tachyarrhythmias in aortic valve stenosis?

BACKGROUND: It is well known that there is a close relation between sudden cardiac death and serious ventricular tachyarrhythmias in patients with aortic valve stenosis (AS). QT dispersion (QTd) reflects the ventricular repolarization heterogeneity and has been proposed as an indicator for ventricular arrhythmias. HYPOTHESIS: This study investigated the QTd and its relevance to the clinical and echocardiographic variables. METHODS: In all, 51 patients (33 men, 18 women, mean age 56 +/- 12) with isolated AS and 51 age- and gender-matched healthy controls comprised the study group. Left ventricular mass index (LVMI) was calculated by the Devereux formula, and we used continuous-wave Doppler (n = 15) and cardiac catheterization (n = 36) for the determination of the maximum aortic valve pressure gradient (PG). RESULTS: Corrected QTd (QTcd) (89 +/- 39 vs. 49 +/- 15 ms, p < 0.001) and LVMI (176 +/- 69 g/m2 vs. 101 +/- 28 g/m2, p < 0.001) in patients with AS were significantly different from those in the control group. The group of 21 patients had a significantly greater number of 24-h mean ventricular premature beats (VPB) and mean number of couplet VT episodes than did the control group (p < 0.05). QTcd also correlated significantly well with LVMI (r = 0.58, p < 0.001), PG (r = 0.41, p = 0.003), and number of 24-h VPB (r = 0.56, p = 0.008). With respect to symptoms (e.g., angina, syncope, and dyspnea) patients without symptoms (n = 19) displayed less QTcd (71 +/- 31 vs. 100 +/- 39 ms, p = 0.007) and less LVMI (144 +/- 80 g/m2 vs. 195 +/- 57 g/m2, p = 0.01) than patients with symptoms. Statistical analysis was similar for all variables with uncorrected QTd values. CONCLUSION: We found that ventricular repolarization heterogeneity was greater in patients with AS than in controls. Our findings also showed that QTd in the patient group correlates well with LVMI, severity of AS, and PG. The present results suggest that serious ventricular arrhythmias in patients with AS may be due to spatial ventricular repolarization abnormality.     

Do elderly Medicare recipients contact physicians appropriately?

OBJECTIVES: This research identified characteristics of persons and their illness episodes that predict appropriate and inappropriate decisions to seek medical care. METHODS: This study analyzes 1,292 health care decisions of 885 elderly members of an HMO in Los Angeles. Illness episodes are divided into three categories based on the expertise of a panel of 22 geriatricians, using a formal mathematical analysis derived from anthropological consensus theory. These categories are physician visit not recommended, physician visit recommended, and physician visit mandatory. Physician contact is regressed on a list of variables derived from Andersen's behavioral model separately for each group of episodes. RESULTS: Although the variables indicating perceived seriousness and duration of the episode consistently predict the decision to contact a physician, regardless of whether that contact is considered appropriate by the geriatrician panel, the variables indicating other illness responses and predisposing personal attributes have less consistent patterns of significance. DISCUSSION: The category of episodes (visit recommended) for which predisposing personal attributes figure most strongly in the treatment decision is the one for which there are no clear cultural directives to action. Implications for health education and policy are drawn from the findings.     

Drug therapy of sustained ventricular tachyarrhythmias. Is there still a role?

This article provides a review of the risks faced by patients with sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) in the absence of a reversible or transient cause so that the goals of therapy can be clearly defined. The therapeutic approaches that have been proposed to achieve these goals are outlined and evidence comparing these various approaches to therapy is then summarized in order to propose an algorithm for the optimal use of antiarrhythmic drug therapies as primary therapy for selected VT/VF patients. Options for the ancillary uses of antiarrhythmic drug therapies in ICD patients are considered.     

What is meant by a "controlled" ventricular rate in atrial fibrillation?

Reduction of a rapid ventricular rate in atrial fibrillation results in a longer diastolic filling period and a higher left ventricular stroke volume but this is offset by reduced contractility and fewer beats per minute; the net effect on cardiac output is uncertain. Sequences of stroke distances were measured by Doppler ultrasound in 60 resting patients with atrial fibrillation to determine the relation between ventricular rate and linear cardiac output. The slope of the cardiac output/ventricular rate relation was positive in all 20 patients with a ventricular rate less than 90 beats per minute and negative in 16 (40%) of 40 patients with a ventricular rate greater than 90 beats per minute. In atrial fibrillation the ventricular rate can be regarded as "controlled" when the cardiac output/ventricular rate slope is positive and "uncontrolled" when the slope is negative--that is when reduction of ventricular rate would lead to increased cardiac output. As so defined, ventricular rate at rest was controlled in every patient when the ventricular rate was less than 90, controlled in 44 (73%) patients when the ventricular rate was 90-140 beats per minute, and uncontrolled in every case when it was greater than 140 beats per minute. Achieving a target ventricular rate of 90 beats per minute in patients with atrial fibrillation at rest would result in control with the least compromise of cardiac output.     

What is meant by a "controlled" ventricular rate in atrial fibrillation?

Reduction of a rapid ventricular rate in atrial fibrillation results in a longer diastolic filling period and a higher left ventricular stroke volume but this is offset by reduced contractility and fewer beats per minute; the net effect on cardiac output is uncertain. Sequences of stroke distances were measured by Doppler ultrasound in 60 resting patients with atrial fibrillation to determine the relation between ventricular rate and linear cardiac output. The slope of the cardiac output/ventricular rate relation was positive in all 20 patients with a ventricular rate less than 90 beats per minute and negative in 16 (40%) of 40 patients with a ventricular rate greater than 90 beats per minute. In atrial fibrillation the ventricular rate can be regarded as "controlled" when the cardiac output/ventricular rate slope is positive and "uncontrolled" when the slope is negative--that is when reduction of ventricular rate would lead to increased cardiac output. As so defined, ventricular rate at rest was controlled in every patient when the ventricular rate was less than 90, controlled in 44 (73%) patients when the ventricular rate was 90-140 beats per minute, and uncontrolled in every case when it was greater than 140 beats per minute. Achieving a target ventricular rate of 90 beats per minute in patients with atrial fibrillation at rest would result in control with the least compromise of cardiac output.     

Left ventricular systolic dysfunction and atrial fibrillation in older people in the community--a need for screening?

BACKGROUND: Heart failure and stroke are major causes of morbidity and mortality in older people. Angiotensin converting enzyme inhibitors improve symptoms and survival in left ventricular systolic dysfunction. Anticoagulants are effective in stroke prevention in atrial fibrillation with aspirin being a less effective alternative. OBJECTIVES: To determine the prevalence of left ventricular systolic dysfunction, health services utilisation and prescribing of diuretics and angiotensin converting enzyme inhibitors in left ventricular systolic dysfunction, and the prevalence of atrial fibrillation and anti-platelet/thrombotic therapy in atrial fibrillation in older people in the community. METHODS: 500 subjects were drawn by two-stage random sampling from 5,002 subjects aged 70 years and over living at home. Subjects were screened for atrial fibrillation and left ventricular systolic dysfunction using electrocardiography and echocardiography. RESULTS: The population prevalence amongst older people of left ventricular systolic dysfunction was 9.8% and of atrial fibrillation 7.8%. More than two-thirds of those with left ventricular systolic dysfunction were not on angiotensin converting enzyme inhibitors. Of those in atrial fibrillation, 35% were taking aspirin, 24% were taking warfarin and 41% were on neither aspirin nor warfarin. Nearly 90% of older people in the community have had contact with their general practitioner over the past year, and over half of those with left ventricular systolic dysfunction have had contact with hospital-based services over the past 2 years. CONCLUSIONS: Left ventricular systolic dysfunction is under-treated in older people in the community. Despite the high level of contact with hospital and community-based services, the majority of those with systolic left ventricular dysfunction are not on angiotensin converting enzyme inhibitors and a significant proportion of those in atrial fibrillation are not on any treatment for stroke prevention.     

Outcome of cardioverter–defibrillator implant in patients with arrhythmogenic right ventricular cardiomyopathy

The aim of the present study was to investigate outcomes of implantable cardioverter–defibrillator (ICD) treatment in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). We reviewed baseline/follow-up data of 15 consecutive ARVC patients (mean age 55 ± 15 years) and 30 randomly drawn patients with coronary artery disease (CAD) (mean age 60 ± 10 years) with matching durations of follow-up (all implanted with ICDs for primary/secondary prevention of sudden death). At implant, appropriate placement of the RV lead was more difficult in ARVC patients. During follow-up (median 41 months), appropriate interventions for any ventricular tachyarrhythmias occurred in 8 (53%) ARVC patients and 17 (57%) CAD patients, but the occurrence of high rate (>240 beats/min) ventricular tachyarrhythmias was higher in ARVC patients. Inappropriate ICD interventions occurred in 5 (33%) ARVC patients and 10 (33%) CAD patients. Lead-related adverse events requiring surgical revision occurred in 7 (47%) ARVC patients as compared with 4 (13%) CAD patients (P = 0.0004). While ICD implantation is highly effective for prevention of sudden death in ARVC, it does carry elevated burdens of long-term lead-related adverse events. These findings underline the need of careful follow-up in ARVC aimed at early recognition of complications that can impair ICD function.