Liam Ring

Incidence of atrial fibrillation detected by implantable loop recorders in unexplained stroke

Objectives: The usefulness of the implantable loop recorder (ILR) with improved atrial fibrillation (AF) detection capability (Reveal XT) and the factors associated with AF in the setting of unexplained stroke were investigated. Methods: A cohort study is reported of 51 patients in whom ILRs were implanted for the investigation of ischemic stroke for which no cause had been found (cryptogenic) following appropriate vascular and cardiac imaging and at least 24 hours of cardiac rhythm monitoring. Results: The patients were aged from 17 to 73 (median 52) years. Of the 30 patients with a shunt investigation, 22 had a patent foramen ovale (73.3%; 95% confidence interval [CI] 56.5%–90.1%). AF was identified in 13 (25.5%; 95% CI 13.1%–37.9%) cases. AF was associated with increasing age (p = 0.018), interatrial conduction block (p = 0.02), left atrial volume (p = 0.025), and the occurrence of atrial premature contractions on preceding external monitoring (p = 0.004). The median (range) of monitoring prior to AF detection was 48 (0–154) days. Conclusion: In patients with unexplained stroke, AF was detected by ILR in 25.5%. Predictors of AF were identified, which may help to target investigations. ILRs may have a central role in the future in the investigation of patients with unexplained stroke.

Anatomy of the mitral valve: understanding the mitral valve complex in mitral regurgitation

Imaging the mitral valve requires an understanding of the normal anatomy and how this complex structure is altered by disease states. Mitral regurgitation is increasingly prevalent. Despite the fall in rheumatic disease, it is the second most common valvular lesion seen in adults in Europe. In this review, the morphology of the normal and abnormal valve is reconsidered in relation to the key structures, with a view to aiding the reader in understanding how this might relate to echocardiographic identification of abnormalities.

Chronic Dipeptidyl Peptidase-4 Inhibition With Sitagliptin Is Associated With Sustained Protection Against Ischemic Left Ventricular Dysfunction in a Pilot Study of Patients With Type 2 Diabetes Mellitus and Coronary Artery Disease

Background—The incretin hormone, glucagon-like peptide-1, promotes myocardial glucose uptake and may improve myocardial tolerance to ischemia. Endogenous glucagon-like peptide-1 (7–36) is augmented by pharmacological inhibition of dipeptidyl peptidase-4. We investigated whether chronic dipeptidyl peptidase-4 inhibition by sitagliptin protected against ischemic left ventricular dysfunction during dobutamine stress in patients with type 2 diabetes mellitus and coronary artery disease. Methods and Results—A total of 19 patients with type 2 diabetes mellitus underwent dobutamine stress echocardiography with tissue Doppler imaging on 2 separate occasions: the first (control) while receiving oral hypoglycemic agents, and the second after the addition of sitagliptin (100 mg once daily) for ≈4 weeks. Sitagliptin increased plasma glucagon-like peptide-1 (7–36) levels and, at peak stress, enhanced both global (ejection fraction, 70.5±7.0 versus 65.7±8.0%; P<0.0001; mitral annular systolic velocity, 11.7±2.6 versus 10.9±2.3 cm/s; P=0.01) and regional left ventricular function, assessed by peak systolic velocity and strain rate in 12 paired, nonapical segments. This was predominantly because of a cardioprotective effect on ischemic segments (strain rate in ischemic segments, −2.27±0.65 versus −1.98±0.58 s−1; P=0.001), whereas no effect was seen in nonischemic segments (−2.19±0.48 versus −2.18±0.54 s−1; P=0.87). At 30 minutes recovery, dipeptidyl peptidase-4 inhibition mitigated the postischemic stunning seen in the control scan. Conclusions—The addition of dipeptidyl peptidase-4 inhibitor therapy with sitagliptin to the treatment regime of patients with type 2 diabetes mellitus and coronary artery disease is associated with a sustained improvement in myocardial performance during dobutamine stress and a reduction in postischemic stunning. Clinical Trial Registration—URL: http://www.isrctn.org. Unique identifier ISRCTN61646154.

Dynamics of the tricuspid valve annulus in normal and dilated right hearts: a three-dimensional transoesophageal echocardiography study

BACKGROUND The tricuspid valve annulus (TVA) is a complex three-dimensional structure that is incompletely understood. Three-dimensional transoesophageal echo (TOE) provides us with the opportunity to examine this structure in detail. METHODS AND RESULTS Fifty patients were included, divided into two groups: controls (n = 20), and dilated right hearts (DRH, n = 30). Three-dimensional zoom images of the TVA were acquired using an iE33 machine and X7-2t transducer. Antero-posterior (AP) diameter, septo-lateral (SL) diameter, area, circumference, and height were measured at 6 points of the cardiac cycle adapting commercially available software designed for assessing the mitral valve (MVQ, Philips). The eccentricity ratio was calculated as AP/SL. The tricuspid annular area decreases during systole in both groups, and is greatest in mid-diastole. The area is significantly larger in the DRH group (mean 1566 mm(2) DRH vs. 1097 mm(2) controls; P < 0.01). The SL diameter increases proportionately more in the DRH group, resulting in a more circular orifice and lower eccentricity ratios (eccentricity ratio mean 1.01 DRH vs. 1.24 controls; P < 0.01). The dynamic diastolic to systolic change in the SL diameter is lost in patients with DRH, contributing to the more circular TVA orifice throughout systole. CONCLUSION Three-dimensional TOE allows us to examine the TVA in great detail. In patients with DRH, the TVA dilates in a SL direction, resulting in a more circular orifice. The dynamic changes of the TVA are lost in patients with DRH, potentially contributing to functional tricuspid regurgitation.

Mechanisms of atrial mitral regurgitation: insights using 3D transoesophageal echo.

AIMS Functional mitral regurgitation (FMR) is a consequence of mitral annular enlargement, leaflet tethering and reduced co-aptation. The importance of the left atrium (LA) as a cause of mitral regurgitation (MR) is less clear. We applied a co-aptation index using three-dimensional (3D) transoesophageal echocardiography to FMR and MR secondary to LA dilatation (atrial mitral regurgitation, AMR). METHODS AND RESULTS Seventy-two patients underwent comprehensive 3D echo studies: FMR (n = 19); AMR (n = 33); and 20 controls. We recorded: LV size and function; LA dimensions; mitral annular area (MVA); and leaflet area in early and late systole. MVA fractional change was defined: (MVA late systole - MVA early systole)/MVA late systole × 100%; the co-aptation index was defined: (leaflet area early systole - leaflet area late systole)/leaflet area early systole × 100%. Despite normal LV size and function in AMR, MVA was increased similarly to FMR (AMR 12.86 cm(2) vs. FMR 12.33 cm(2), P = ns; both P < 0.01 vs. controls 8.83 cm(2)), and MVA fractional change similarly reduced (AMR 5.1% vs. FMR 6.3%; P = ns; both P < 0.001 vs. controls 14.6%). The co-aptation index was reduced in both MR groups (FMR 6.6% vs. AMR 7.0%, P = ns; both P < 0.001 vs. controls 19.6%). After multivariate analysis, the co-aptation index (χ(2) = 41.2) and MVA fractional change (χ(2) = 22.1) remained the strongest predictors of MR (both P < 0.001 for the model). A co-aptation index of ≤13% was 96% sensitive and 90% specific for the presence of MR. CONCLUSION LA dilatation leads to MVA enlargement, reduced leaflet co-aptation and MR even without LV dilatation. A co-aptation index describes this in vivo. This work provides insights into the mechanism of AMR.

The prevalence and impact of deep clefts in the mitral leaflets in mitral valve prolapse

AIMS Deep clefts are a cause of early failure of mitral valve repair, but it is not known whether clefts represent normal morphology, or whether they occur more frequently in mitral valve prolapse (MVP). METHODS AND RESULTS Deep clefts were defined as indentations extending ≥ 50% of the depth of the mitral valve leaflet. Using trans-oesophageal echo (TOE), 3D zoom images were acquired of the mitral valve in 176 patients: 76 patients with MVP, 43 patients with alternative causes of mitral regurgitation (MR), and 57 controls. Three-dimensional TOE results were corroborated with findings made at surgery for a subset of patients who subsequently underwent mitral valve surgery. An assessment of the proportion of the valve that was prolapsing was documented, and correlated to the number of clefts. The relationship of clefts to the region of prolapse or flail was recorded. Three-dimensional TOE was 93% sensitive and 92% specific for detecting clefts. Clefts were documented in 84% of patients with MVP, but significantly less frequently in patients with alternative MR (16%; P < 0.001) and controls (12%, P < 0.001). Clefts always appear in prolapsing regions or framing them, and the number of clefts increased in patients with more extensive prolapse. CONCLUSION Clefts are frequently seen in MVP, but are uncommon in patients without this diagnosis. They occur in greater numbers as a larger proportion of the valve prolapses. They may play an important role in the development of MVP.

Direct stenting is an independent predictor of improved survival in patients undergoing primary percutaneous coronary intervention for ST elevation myocardial infarction

Aims: Randomised trials have shown that direct stenting (DS) is associated with improved markers of reperfusion during primary percutaneous coronary intervention (PPCI) for ST elevation myocardial infarction (STEMI). However, data evaluating its impact on long-term clinical outcomes are lacking. We set out to evaluate the effect of DS on mortality in a contemporary population of patients undergoing PPCI for STEMI. Methods: Consecutive patients undergoing PPCI for STEMI at two high-volume UK heart attack centres between September 2008– December 2010 (n=1562) were included in the analysis. Local databases were analysed for patient demographics, as well as details on PPCI strategy, including use of DS versus predilatation (PD) followed by stenting, manual thrombus aspiration (MT) and glycoprotein IIb/IIIa inhibitors (GPIs). National databases were interrogated for in-hospital, 30-day and one-year mortality. To determine the impact of PPCI strategy on one-year survival, multivariate logistic analysis was performed. Results: Altogether 489 patients underwent DS (31.3%) and 1073 (68.7%) received PD prior to stenting. Patients receiving DS had reduced mortality at 30 days (2.04 versus 4.66%, p=0.01) and one year (3.27 versus 8.48%, p=0.0001). After multivariate adjustment, PD remained an independent predictor of one-year mortality (odds ratio 2.42, 95% confidence interval 1.08–5.45, p=0.032) along with age, cardiogenic shock, number of diseased vessels, and left main or proximal left anterior descending artery intervention. However, neither GPI use nor MT improved survival in either univariate or multivariate analyses. Conclusions: In a contemporary, unselected population of patients undergoing PPCI for STEMI, DS – when compared with stenting after PD – is independently predictive of improved 30-day and one-year survival.

Development of a multiparametric score to predict left ventricular remodelling and prognosis after cardiac resynchronization therapy

Optimal delivery of CRT requires appropriate patient selection and device implantation. Echocardiographic predictors of CRT response individually appear to enhance patient selection, but do not fully reflect the complex underlying myocardial dysfunction. We hypothesized that a multiparametric approach would offer greater predictive value and sought to derive a score incorporating baseline characteristics including: dyssynchrony, LV function, and LV lead position.

The pivotal role of echocardiography in cardiac sources of embolism

Stroke is a leading cause of morbidity and mortality and is the third commonest cause of death in Europe. Clinical history examination and basic investigations including an electrocardiogram may shed light on the potential cardiac cause. Echocardiography plays a pivotal role in the assessment of embolic stroke. The hierarchy of echocardiography investigations begins with a standard transthoracic echocardiography study and may be proceeded by a bubble contrast transthoracic and a transoesophageal echo study. This article discusses the crucial role echocardiography has assumed in the assessment of stroke patients and describes the cardiac sources responsible.

Impact of methodology and the use of allometric scaling on the echocardiographic assessment of the aortic root and arch: a study by the Research and Audit Sub-Committee of the British Society of Echocardiography

The aim of the study is to establish the impact of 2D echocardiographic methods on absolute values for aortic root dimensions and to describe any allometric relationship to body size. We adopted a nationwide cross-sectional prospective multicentre design using images obtained from studies utilising control groups or where specific normality was being assessed. A total of 248 participants were enrolled with no history of cardiovascular disease, diabetes, hypertension or abnormal findings on echocardiography. Aortic root dimensions were measured at the annulus, the sinus of Valsalva, the sinotubular junction, the proximal ascending aorta and the aortic arch using the inner edge and leading edge methods in both diastole and systole by 2D echocardiography. All dimensions were scaled allometrically to body surface area (BSA), height and pulmonary artery diameter. For all parameters with the exception of the aortic annulus, dimensions were significantly larger in systole (P<0.05). All aortic root and arch measurements were significantly larger when measured using the leading edge method compared with the inner edge method (P<0.05). Allometric scaling provided a b exponent of BSA0.6 in order to achieve size independence. Similarly, ratio scaling to height in subjects under the age of 40 years also produced size independence. In conclusion, the largest aortic dimensions occur in systole while using the leading edge method. Reproducibility of measurement, however, is better when assessing aortic dimensions in diastole. There is an allometric relationship to BSA and, therefore, allometric scaling in the order of BSA0.6 provides a size-independent index that is not influenced by the age or gender.