Ventricular arrhythmias in arrhythmic mitral valve syndrome-a prospective continuous long-term cardiac monitoring study.

AIMS: Arrhythmic mitral valve syndrome is linked to life-threatening ventricular arrhythmias. The incidence, morphology and methods for risk stratification are not well known. This prospective study aimed to describe the incidence and the morphology of ventricular arrhythmia and propose risk stratification in patients with arrhythmic mitral valve syndrome. METHODS: Arrhythmic mitral valve syndrome patients were monitored for ventricular tachyarrhythmias by implantable loop recorders (ILR) and secondary preventive implantable cardioverter-defibrillators (ICD). Severe ventricular arrhythmias included ventricular fibrillation, appropriate or aborted ICD therapy, sustained ventricular tachycardia and non-sustained ventricular tachycardia with symptoms of hemodynamic instability. RESULTS: During 3.1 years of follow-up, severe ventricular arrhythmia was recorded in seven (12%) of 60 patients implanted with ILR [first event incidence rate 4% per person-year, 95% confidence interval (CI) 2-9] and in four (20%) of 20 patients with ICD (re-event incidence rate 8% per person-year, 95% CI 3-21). In the ILR group, severe ventricular arrhythmia was associated with frequent premature ventricular complexes, more non-sustained ventricular tachycardias, greater left ventricular diameter and greater posterolateral mitral annular disjunction distance (all P < 0.02). CONCLUSIONS: The yearly incidence of ventricular arrhythmia was high in arrhythmic mitral valve syndrome patients without previous severe arrhythmias using continuous heart rhythm monitoring. The incidence was even higher in patients with secondary preventive ICD. Frequent premature ventricular complexes, non-sustained ventricular tachycardias, greater left ventricular diameter and greater posterolateral mitral annular disjunction distance were predictors of first severe arrhythmic event.

The Mitral Annulus Disjunction Arrhythmic Syndrome.

BACKGROUND: Mitral annulus disjunction (MAD) is an abnormal atrial displacement of the mitral valve leaflet hinge point. MAD has been associated with mitral valve prolapse (MVP) and sudden cardiac death. OBJECTIVES: The purpose of this study was to describe the clinical presentation, MAD morphology, association with MVP, and ventricular arrhythmias in patients with MAD. METHODS: The authors clinically examined patients with MAD. By echocardiography, the authors assessed the presence of MVP and measured MAD distance in parasternal long axis. Using cardiac magnetic resonance (CMR), the authors assessed circumferential MAD in the annular plane, longitudinal MAD distance, and myocardial fibrosis. Aborted cardiac arrest and sustained ventricular tachycardia were defined as severe arrhythmic events. RESULTS: The authors included 116 patients with MAD (age 49 ± 15 years; 60% female). Palpitations were the most common symptom (71%). Severe arrhythmic events occurred in 14 (12%) patients. Longitudinal MAD distance measured by CMR was 3.0 mm (interquartile range [IQR]: 0 to 7.0 mm) and circumferential MAD was 150° (IQR: 90° to 210°). Patients with severe arrhythmic events were younger (age 37 ± 13 years vs. 51 ± 14 years; p = 0.001), had lower ejection fraction (51 ± 5% vs. 57 ± 7%; p = 0.002) and had more frequently papillary muscle fibrosis (4 [36%] vs. 6 [9%]; p = 0.03). MVP was evident in 90 (78%) patients and was not associated with ventricular arrhythmia. CONCLUSIONS: Ventricular arrhythmias were frequent in patients with MAD. A total of 26 (22%) patients with MAD did not have MVP, and MVP was not associated with arrhythmic events, indicating MAD itself as an arrhythmogenic entity. MAD was detected around a large part of the mitral annulus circumference and was interspersed with normal tissue.

Cardiac Magnetic Resonance-Measured Left Atrial Volume and Function and Incident Atrial Fibrillation: Results From MESA (Multi-Ethnic Study of Atherosclerosis).

BACKGROUND: Early detection of structural changes in left atrium (LA) before atrial fibrillation (AF) development could be helpful in identification of those at higher risk for AF. Using cardiac magnetic resonance imaging, we examined the association of LA volume and function, and incident AF in a multiethnic population free of clinical cardiovascular diseases. METHODS AND RESULTS: In a case-cohort study embedded in MESA (Multi-Ethnic Study of Atherosclerosis), baseline LA size and function assessed by cardiac magnetic resonance feature-tracking were compared between 197 participants with incident AF and 322 participants randomly selected from the whole MESA cohort. Participants were followed up for 8 years. Incident AF cases had a larger LA volume and decreased passive, active, and total LA emptying fractions and peak global LA longitudinal strain (peak LA strain) at baseline. In multivariable analysis, elevated LA maximum volume index (hazard ratio, 1.38 per SD; 95% confidence interval, 1.01-1.89) and decreased peak LA strain (hazard ratio, 0.68 per SD; 95% confidence interval, 0.48-0.96), and passive and total LA emptying fractions (hazard ratio for passive LA emptying fractions, 0.55 per SD; 95% confidence interval, 0.40-0.75 and hazard ratio for active LA emptying fractions, 0.70 per SD; 95% confidence interval, 0.52-0.95), but not active LA emptying fraction, were associated with incident AF. CONCLUSIONS: Elevated LA volumes and decreased passive and total LA emptying fractions were independently associated with incident AF in an asymptomatic multiethnic population. Including LA functional variables along with other risk factors of AF may help to better risk stratify individuals at risk of AF development.

Association of CMR-measured LA function with heart failure development: results from the MESA study.

OBJECTIVES: The goal of this study was to assess the association between left atrial (LA) volume and function measured with feature-tracking cardiac magnetic resonance (CMR) and development of heart failure (HF) in asymptomatic individuals. BACKGROUND: Whether alterations of LA structure and function precede or follow HF development remains incompletely understood. We hypothesized that significant alterations of LA deformation and architecture precede the development of HF in the general population. METHODS: In a case-control study nested in MESA (Multi-Ethnic Study of Atherosclerosis), baseline LA volume and function assessed using CMR feature-tracking were compared between 112 participants with incident HF (mean age 68.4 ± 8.2 years; 66% men) and 224 age- and sex-matched controls (mean age 67.7 ± 8.9 years; 66% men). Participants were followed up for 8 years. All individuals were in normal sinus rhythm at the time of imaging, without any significant valvular abnormalities and free of clinical cardiovascular diseases. RESULTS: Individuals with incident HF had greater maximal and minimal LA volume indexes (LAVImin) than control subjects (40 ± 13 mm(3)/m(2) vs. 33 ± 10 mm(3)/m(2) [p <0.001] for maximal LA index and 25 ± 11 mm(3)/m(2) vs. 17 ± 7 mm(3)/m(2) [p <0.001] for LAVImin). The HF case subjects also had smaller global peak longitudinal atrial strain (PLAS) (25 ± 11% vs. 38 ± 16%; p <0.001) and lower LA emptying fraction (40 ± 11% vs. 48 ± 9%; p <0.001) at baseline. After adjustment for traditional cardiovascular risk factors, left ventricular mass, and N-terminal pro-B-type natriuretic peptide, global PLAS (odds ratio: 0.36 per SD [95% confidence interval: 0.22 to 0.60]) and LAVImin (odds ratio: 1.65 per SD [95% confidence interval: 1.04 to 2.63]) were independently associated with incident HF. CONCLUSIONS: Deteriorations in LA structure and function preceded development of HF. Lower global PLAS and higher LAVImin, measured using CMR feature-tracking, were independent markers of incident HF in a multiethnic population of asymptomatic individuals.

Usefulness of radial strain mapping by multidetector computer tomography to quantify regional myocardial function in patients with healed myocardial infarction.

We introduce and evaluate strain mapping by multidetector computer tomography as a new noninvasive method for assessment of myocardial function. In patients (n = 16) with healed myocardial infarction, peak systolic radial strain was measured by automated pixel pattern matching analysis of multiple left ventricular 64-slice multidetector computer tomographic short-axis recordings. For comparison, radial strain and myocardial infarct extent were measured by tagged magnetic resonance imaging (MRI) and late enhancement MRI, respectively. In a linear mixed model analysis, myocardial infarct extent was a strong predictor of segmental strain by multidetector computer tomography (beta = -0.44, p <0.0001). Strain was significantly different among noninfarcted (0%), nontransmurally infarcted (0% to 50%), and transmurally infarcted (>50%) segments (p <0.001) and between infarcted and noninfarcted border zone segments (p <0.001). There was a close relation between strain by multidetector computer tomography and by tagged MRI (mean difference -7.4 +/- 11.7%, r = 0.68, p <0.0001). Mean time-to-peak systolic strain was 324 +/- 42 ms by multidetector computer tomography and 335 +/- 56 ms by tagged MRI (mean difference 11 +/- 40 ms). In conclusion, to our knowledge this is the first study to demonstrate that regional myocardial function can be quantified by multidetector computer tomographic imaging, indicating that assessment of radial strain by multidetector computer tomography might be a useful tool in the evaluation of patients with cardiovascular diseases.