ObjectiveMitral annular disjunction (MAD) is an abnormality linked to mitral valve prolapse (MVP), possibly associated with malignant ventricular arrhythmias. We assessed the agreement among different imaging techniques for MAD identification and measurement.Methods131 patients with MVP and significant mitral regurgitation undergoing transthoracic echocardiography (TTE) and cardiac magnetic resonance (CMR) were retrospectively enrolled. Transoesophageal echocardiography (TOE) was available in 106 patients. MAD was evaluated in standard long-axis views (four-chamber, two-chamber, three-chamber) by each technique.ResultsConsidering any-length MAD, MAD prevalence was 17.3%, 25.5%, 42.0% by TTE, TOE and CMR, respectively (p<0.05). The agreement on MAD identification was moderate between TTE and CMR (κ=0.54, 95% CI 0.49 to 0.59) and good between TOE and CMR (κ=0.79, 95% CI 0.74 to 0.84). Assuming CMR as reference and according to different cut-off values for MAD (≥2 mm, ≥4 mm, ≥6 mm), specificity (95% CI) of TTE and TOE was 99.6 (99.0 to 100.0)% and 98.7 (97.4 to 100.0)%; 99.3 (98.4 to 100.0)% and 97.6 (95.8 to 99.4)%; 97.8 (96.2 to 99.3)% and 93.2 (90.3 to 96.1)%, respectively; sensitivity (95% CI) was 43.1 (37.8 to 48.4)% and 74.5 (69.4 to 79.5)%; 54.0 (48.7 to 59.3)% and 88.9 (85.2 to 92.5)%; 88.0 (84.5 to 91.5)% and 100.0 (100.0 to 100.0)%, respectively. MAD length was 8.0 (7.0-10.0), 7.0 (5.0-8.0], 5.0 (4.0-7.0) mm, respectively by TTE, TOE and CMR. Agreement on MAD measurement was moderate between TTE and CMR (ρ=0.73) and strong between TOE and CMR (ρ=0.86).ConclusionsAn integrated imaging approach could be necessary for a comprehensive assessment of patients with MVP and symptoms suggestive for arrhythmias. If echocardiography is fundamental for the anatomic and haemodynamic characterisation of the MV disease, CMR may better identify small length MAD as well as myocardial fibrosis.
Background-In patients with heart failure (HF), during maximal cardiopulmonary exercise test, anaerobic threshold (AT)is not always identified. We evaluated whether this finding has a prognostic meaning. Methods and Results-We recruited and prospectively followed up, in 14 dedicated HF units, 3058 patients with systolic (left ventricular ejection fraction <40%) HF in stable clinical conditions, New York Heart Association class I to III, who underwent clinical, laboratory, echocardiographic, and cardiopulmonary exercise test investigations at study enrollment. We excluded 921 patients who did not perform a maximal exercise, based on lack of achievement of anaerobic metabolism (peak respiratory quotient ≤1.05). Primary study end point was a composite of cardiovascular death and urgent cardiac transplant, and secondary end point was all-cause death. Median follow-up was 3.01 (1.39-4.98) years. AT was identified in 1935 out of 2137 patients (90.54%). At multivariable logistic analysis, failure in detecting AT resulted significantly in reduced peak oxygen uptake and higher metabolic exercise and cardiac and kidney index score value, a powerful prognostic composite HF index (P<0.001). At multivariable analysis, the following variables were significantly associated with primary study end point: peak oxygen uptake (% pred; P<0.001 T he anaerobic threshold (AT) concept is based on the principle that energy production shifts from an aerobic metabolism to a metabolism that combines both anaerobic and aerobic patterns during a progressively increasing workload exercise.1,2 According to the concept of threshold, the shift of metabolic pathway during incremental exercise must be more or less simultaneous among active muscular fibers. Therefore, the distribution of blood flow during exercise to and into muscles, the resistance to O 2 flow between capillaries and mitochondria, the type of muscular fibers, and their metabolic capability must be relatively homogeneous.3 This is not always the case in patients with heart failure (HF) who have an uneven distribution of blood flow to muscles and an uneven use of O 2 , so that, for example, an important percentage of subjects with HF increase their capillary PO 2 toward the end of exercise.4-7 Inhomogeneity of blood flow distribution, of O 2 flow resistance, and of O 2 use should widen the time frame where anaerobiosis starts to develop among the muscular fibers, in few cases making the threshold indefinable. If this hypothesis is correct, then AT should be more frequently undetectable in patients with a more severe disease. Clinical Perspective on p 987From a clinical point of view, the value of oxygen uptake (VO 2 ) at AT is used for grading the severity of HF or the effects of therapy, or to assess cardiovascular risk in case of surgery, 9-18 and it has been proposed as an alternative to peak VO 2 , being it independent of patients' motivation, exercise protocol, and exercise duration. 19 However, even in the presence of anaerobic metabolism, AT is not identified in a large num...
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