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Biomedical subjects

Iqwal Mangat

Publications and source records attributed to Iqwal Mangat.

12 recordsLinked to original sources
PubMed2006

Psychological correlates of quality of life in atrial fibrillation.

OBJECTIVE: Atrial fibrillation (AF) is associated with significant health-related quality of life (QoL) impairments. Markers of heart disease severity have explained little variance in QoL and it is unclear what other factors will better account for the observed differences in adjustment. We examined whether specific personality traits and illness management styles would help explain the severity of QoL impairments reported in this population. METHODS: Patients with AF (N = 93) completed validated questionnaires measuring disease burden (dependent variables: physical and mental QoL, symptom severity, psychological distress), personality (independent variables: anxiety sensitivity, optimism), and illness management style (mediating variable: symptom preoccupation). Hypothesized relationships were evaluated using mediation models. RESULTS: Anxiety sensitivity was associated with poorer physical and mental QoL, greater symptom severity, and higher distress. Optimism was correlated with better mental QoL and lower distress, but unrelated to physical QoL and symptom severity. Symptom preoccupation significantly mediated the relationships between anxiety sensitivity and each of the QoL measures, as well as the relationships between optimism and mental well-being. CONCLUSIONS: Personality traits and illness management styles are important to consider when assessing the impact of AF on QoL. The data support a cognitive-behavioral model that explains the direct and indirect relationships between psychological predictors and multiple indices of QoL.

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PubMed2006

Gender differences and quality of life in atrial fibrillation: the mediating role of depression.

OBJECTIVE: This study investigated gender differences, depression, and health-related quality of life (QoL) in a cross-sectional sample of patients with atrial fibrillation (AF). METHODS: This cross-sectional study involved a convenience sample of AF patients from two tertiary-care clinics in Toronto, Canada. Ninety-three AF patients completed psychometrically validated measures of generic QoL and depression. Mediation analyses evaluated the relationship between gender and QoL using depression as mediating variable. RESULTS: Relative to male patients, female patients reported lower physical, but not mental, QoL. Gender was associated with both depression and physical QoL, while depression was correlated with poorer physical QoL. Path analyses demonstrated that depression significantly mediated the relationship between gender and physical QoL. CONCLUSION: Among AF patients, female patients report lower physical QoL relative to male patients, and this relationship may be mediated by self-reported symptoms of depression. Albeit correlational, the findings underscore the need to develop a better understanding of the role of depression in physical QoL, especially when considering the burden of AF in women.

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PubMed2005

Site specificity of transverse crista terminalis conduction in patients with atrial flutter.

INTRODUCTION: The causes of transcristal conduction (TC) in patients with atrial flutter (AFL) are unknown. METHODS AND RESULTS: In two groups of patients referred for AFL ablation, 36 had cavotricuspid isthmus (CTI) dependent flutter (Group I) and 24 had lower (n = 21) or upper loop reentry (n = 5) (Group II). After ablation, isthmus block was evaluated by pacing from the coronary sinus (CS) and low lateral right atrium and by alternative techniques, including mapping with electrodes spanning the CTI or electroanatomic mapping. After bidirectional CTI block was verified, 21/36 (58%) in Group I showed TC with CS pacing, including low TC in 16 (including 11 showing "pseudo" CTI conduction), higher TC in 6 and multiple breaks in 3. However, 8 with low TC during CS pacing showed unidirectional block by pacing outside of the CS os. Twelve (50%) in Group II had TC during CS pacing after bidirectional CTI block, with low TC in 5 (2 mimicking residual CTI conduction) and higher breaks in 9. There was no significant difference in the incidence of TC during CS pacing after CTI block between groups. In seven autopsied hearts, the muscle orientation between the proximal CS musculature and Eustachian ridge were examined. Muscular connections between the CS and Eustachian ridge coursing toward the orifice of inferior vena cava were found in one of the hearts. CONCLUSIONS: It is concluded that in patients with bidirectional CTI block, pacing from the CS may be associated with TC mimicking a conduction leak through the isthmus. Pacing just outside the CS os helps distinguish pseudo from true isthmus block.

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PubMed2004

Long-term comparison of the implantable cardioverter defibrillator versus amiodarone: eleven-year follow-up of a subset of patients in the Canadian Implantable Defibrillator Study (CIDS).

BACKGROUND: The implantable cardioverter defibrillator (ICD) is superior to amiodarone for secondary prophylaxis of sudden cardiac death. However, the magnitude of this benefit over long-term follow-up is not known. Thus, our objective was to evaluate the long-term consequences of using amiodarone versus an ICD as first-line monotherapy in patients with a prior history of sustained ventricular tachycardia/ventricular fibrillation or cardiac arrest. METHODS AND RESULTS: A total of 120 patients were enrolled at St Michael's Hospital in the Canadian Implantable Defibrillator Study (CIDS) and were randomly assigned to receive either amiodarone (n=60) or an ICD (n=60). The treatment strategy was not altered after the end of CIDS unless the initial assigned therapy was not effective or was associated with serious side effects. After a mean follow-up of 5.6+/-2.6 years, there were 28 deaths (47%) in the amiodarone group, compared with 16 deaths (27%) in the ICD group (P=0.0213). Total mortality was 5.5% per year in the amiodarone group versus 2.8% per year in the ICD group (hazard ratio of amiodarone: ICD, 2.011; 95% confidence interval, 1.087 to 3.721; P=0.0261). In the amiodarone group, 49 patients (82% of all patients) had side effects related to amiodarone, of which 30 patients (50% of all patients) required discontinuation or dose reduction; 19 patients crossed over to ICD because of amiodarone failure (n=7) or side effects (n=12). CONCLUSIONS: In a subset of CIDS, the benefit of the ICD over amiodarone increases with time; most amiodarone-treated patients eventually develop side effects, have arrhythmia recurrences, or die.

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PubMed2004

The burden of atrial fibrillation: should we abandon antiarrhythmic drug therapy?

Atrial fibrillation (AF) is the most common sustained arrhythmia, exacting a substantial toll in cardiovascular morbidity and mortality. Until recently, the prevailing philosophy has been that restoration and maintenance of normal sinus rhythm, as opposed to control of ventricular response rate, was the optimal approach to treatment of AF. A series of landmark trials (AFFIRM, RACE, STAF, and PIAF) have called this strategy into question, suggesting outcomes are equivalent with both approaches. These data do not mean that rhythm control is not beneficial, but highlight the limitations of current therapies to achieve and maintain sinus rhythm. Limitations of the rhythm-control strategy may be related to our difficulty in accurately documenting symptomatic benefit from this approach, the lack of efficacy and excessive adverse-effect burden associated with currently available antiarrhythmic agents, and selection biases in the enrollment of patients in clinical trials of rhythm control versus rate control, making the trials incompletely representative of the population eligible for therapy. New pharmacologic agents under development feature increased atrial selectivity or multi-channel-blocking properties (or both). As a result, these compounds may be more effective in prolonging atrial refractoriness and may also have reduced proarrhythmic potential. It is premature to abandon the concept of rhythm control in AF until we have trials designed to include younger and highly symptomatic patients, more sensitive tools to measure symptomatic improvement, and safer, more effective antiarrhythmic agents.

Anti-Arrhythmia Agents↗
PubMed2003

Optimizing the detection of bidirectional block across the flutter isthmus for patients with typical isthmus-dependent atrial flutter.

The purpose of this study was to show that multipolar electrographic recordings along the subeustachian isthmus (SI) can better differentiate slow conduction from complete isthmus block after atrial flutter ablation, leading to a lower incidence of recurrent atrial flutter (Afl). Despite the presence of various techniques to identify bidirectional conduction block (BDB) after isthmus ablation for typical Afl, several studies, including a report from a national registry, suggest that radiofrequency ablation is still associated with a 15% recurrence rate. Thus, techniques that can distinguish slow conduction from complete isthmus block have the potential for reducing long-term recurrences. We evaluated patients who underwent radiofrequency ablation for typical isthmus-dependent Afl. Patients were separated into 2 groups. Group A underwent assessment of BDB with conventional methods. In group B, BDB was assessed by placing a multipolar catheter along the floor of the SI, pacing adjacent to the line of radiofrequency application, and assessing electrographic activation on either side. One hundred thirty-one cases of Afl ablation were analyzed (86 in group A, 45 in group B). Over a mean follow-up period of 17 months, recurrence rates of Afl were 16.5% in group A and 4.3% in group B (p = 0.043). Thus, assessment of BDB by placement of a multipolar catheter across the SI after ablation of typical Afl is associated with a significant reduction in long-term recurrence of Afl.

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PubMed2003

Mechanism of conversion of atypical right atrial flutter to atrial fibrillation.

The purpose of this study was to explore the mechanisms of conversion from atypical atrial flutter (AFL) to atrial fibrillation (AF), and the long-term results of cavotricuspid isthmus ablation in these patients. We retrospectively reviewed the records of 221 patients with typical AFL referred to our hospital for ablation. A total of 25 patients had atypical AFL, and cavotricuspid isthmus ablation was performed in 23 with isthmus-dependent atypical AFL, as well as in 180 patients with typical counterclockwise and/or clockwise AFL. In all, 13 spontaneous transitions from atypical AFL to AF were documented in 11 of 17 patients. Before AF, a pattern of lower loop reentry was observed in 11 of 13 patients (85%) and upper loop reentry in 3 (1 had both). Multiple early breaks along the tricuspid annulus during AFL were noted in 6 of 13 patients (46%). Among the 13 transitions, discrete atrial premature complexes before AF were found in 5 patients with lower loop reentry and in 1 with upper loop reentry (46%). In the remaining patients, a more rapid atrial rhythm was involved in the development of AF with a pulmonary venous focus in 2. In some cases, additional "breaks" in the functional line of block occurred before the development of AF. There was a significant increased incidence of AF (68%) in those with atypical AFL compared with those with typical AFL (38%) (p = 0.004). After a mean follow-up of 28 +/- 9 months for the atypical group and 18 +/- 11 months for the typical group, the AF recurrence rate was similar (57% vs 48%, p = 0.4). Discrete atrial premature complexes or atrial tachycardia may initiate AF either directly or by producing further breaks in lines of functional block. Bidirectional cavotricuspid isthmus block is associated with cure or control of AF in approximately 50% of patients with AFL.

Atrial Fibrillation↗
PubMed2003

Quality of life variables in the selection of rate versus rhythm control in patients with atrial fibrillation: observations from the Canadian Trial of Atrial Fibrillation.

Many patients with atrial fibrillation develop symptoms attributable to the cardiac arrhythmia itself. These symptoms may be improved either by restoring sinus rhythm or by controlling the rapid and irregular ventricular response that often accompanies this arrhythmia. One of the principal goals of therapy of atrial fibrillation management is improvement of patient symptoms; it is important to quantify these symptoms by some form of quality of life analysis. The Canadian Trial of Atrial Fibrillation (CTAF) was a multi-centre randomized clinical trial of amiodarone compared with either propafenone or sotalol in patients with recent atrial fibrillation. The quality of life (QOL) substudy of CTAF was a prospective, comprehensive assessment of quality of life of patients enrolled in CTAF. Summary measures of physical and mental health on the generic QOL scale (SF-36) improved significantly with treatment from baseline to 3 months (41.9 +/- 9.6 to 43.7 +/- 9.2, p = 0.001 for the physical component and 47.5 +/- 10.4 to 49.0 +/- 9.8, p = 0.023 for the mental component). On an arrhythmia specific scale (SCL), a significant and larger improvement was noted from baseline to 3 months in both arrhythmia symptom frequency and severity (symptom frequency from 20.4 +/- 9.4 to 16.2 +/- 9.5, symptom severity from 16.7 +/- 8.2 to 12.9 +/- 7.6, both p < 0.001). The quality of life improvements were similar in the amiodarone group compared to the sotalol or propafenone groups, both for the SF-36 and the disease-specific symptom checklist (SCL) measures. In contrast, an atrial fibrillation severity scale (AFSS) did show differences between the assigned drug therapies, which were associated with different rates of arrhythmia recurrence in the parent study. By 3 months global well-being was significantly worse for patients who had recurrent atrial fibrillation compared to those who did not (6.9 +/- 1.8 versus 7.4 +/- 1.8, p = 0.04). Similarly, symptom severity at 3 months was 11.8 +/- 7.4 for patients without recurrence, compared to 14.8 +/- 7.4 for those with recurrence ( p = 0.001). Interestingly, none of the usual clinical variables that might be perceived to be associated with quality of life, e.g., male versus female sex, age, NYHA class, beta blocker use, and ejection fraction, had much impact on subjective quality of life measures. Quality of life improves with treatment atrial fibrillation and at least some of these improvements are related to the restoration and maintenance of sinus rhythm.

Amiodarone↗
PubMed2003

Role of amiodarone in the era of the implantable cardioverter defibrillator.

Amiodarone is one of the most frequently used antiarrhythmic drugs in clinical practice. In patients with atrial fibrillation, in whom rhythm control is judged desirable, amiodarone is the most effective therapy. Amiodarone effectively prevents atrial fibrillation and may improve quality of life, but there is no evidence that it decreases mortality or severe morbidity in atrial fibrillation. In patients at risk for life-threatening ventricular arrhythmias, amiodarone may decrease mortality to a small degree, but the evidence for this benefit is incomplete. Patients with implantable cardioverter defibrillators frequently require antiarrhythmic drug therapy, especially to treat electrical storm. Amiodarone is useful in these patients; however, it may increase defibrillation thresholds in some patients. In patients with out-of-hospital DC shock-resistant VF, amiodarone is the most effective antiarrhythmic drug available to assist in resuscitation. Amiodarone is a complicated drug, and its optimal use requires careful patient surveillance with respect to potential adverse effects.

Amiodarone↗
PubMed2003

Isolated bundle branch block and left ventricular dysfunction.

BACKGROUND: Population studies have identified the presence of bundle branch block (BBB) as a risk factor for increased mortality in patients with known cardiac disease. It is unknown how chronic ventricular dyssynchrony resulting solely from conduction delay affects ventricular function. METHODS AND RESULTS: Subjects were retrospectively identified from the University of California, San Francisco, electrocardiogram database with QRS prolongation. Subjects who had no evidence of heart disease and had baseline and serial studies evaluating ongoing risk of coronary artery disease status and left ventricular function were followed over time. Documentation of a minimum of 2 serial evaluations of cardiac status were present in a total of 51/176 (20%) subjects with isolated BBB who constitute the study population. After a mean follow-up of 52 +/- 45 months-adjusting for differences due to age, sex, the presence of hypertension, hyperlipidemia, and diabetes mellitus-left ventricular ejection fraction diminished by -7.3 +/- 12% per year in the isolated left BBB cohort versus -1.9 +/- 4% in isolated right BBB cohort and -1.1 +/- 3% reduction in the isolated nonspecific intraventricular conduction delay cohort (P =.019). CONCLUSIONS: Left bundle branch block itself may be a cause of ventricular dysfunction.

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