Pre-operative left atrial mechanical function predicts risk of atrial fibrillation following cardiac surgery.

OBJECTIVES: The purpose of this study was to examine whether left atrial (LA) mechanical function, as measured by LA total emptying fraction (TEF), is a predictor for the development of post-operative atrial fibrillation (POAF) following cardiac surgery. BACKGROUND: POAF is an important and frequent complication of cardiac surgery. LA enlargement has been reported to be a risk factor for POAF, but the relationship between LA mechanical function and POAF is not well understood. We examined the relationship between pre-operative LA function and POAF in patients without a history of atrial fibrillation. METHODS: A total of 101 subjects (mean age 64 ± 13 years) underwent pre-operative transthoracic echocardiograms and were followed for occurrence of POAF during the hospitalization for cardiac surgery. The left atrial maximum volume (LAVmax) and left atrial minimum volume (LAVmin) were measured and indexed to body surface area (LAVmaxI and LAVminI, respectively). LA TEF was calculated as: {[(LAVmax - LAVmin)/LAVmax] × 100%}. Univariate and multivariate analyses examined clinical and echocardiographic predictors of POAF. RESULTS: POAF occurred in 41% of subjects. Mean LA TEF was 49 ± 15%, mean LAVmaxI was 38 ± 15 ml/m(2), and mean LAVminI was 20 ± 13 ml/m(2). Age, LA TEF, and LAVminI were independent predictors of POAF. LA TEF was lower in patients with POAF compared with those without POAF (43 ± 15% vs. 55 ± 13%, p < 0.001), and patients with a LA TEF <50% had a high risk of POAF (odds ratio: 7.94, 95% confidence interval: 3.23 to 19.54, p < 0.001). Compared with LAVmaxI >32 ml/m(2), LA TEF <50% had higher discriminatory power for POAF, which remained significantly higher when adjusted for age (p = 0.04). CONCLUSIONS: LA TEF is an independent predictor of POAF and is a stronger predictor of POAF than LAVmaxI is. Impaired LA mechanical function may help to identify patients who are most likely to benefit from prophylaxis for POAF.

Echocardiographic characterization of left ventricular apical hypoplasia accompanied by a patent ductus arteriosus.

Left ventricular (LV) apical hypoplasia is an unusual, recently identified cardiomyopathy, whose clinical course is uncertain. In this report, we describe a case of this cardiomyopathy occurring in an asymptomatic 50-year-old male with a remote history of a surgically corrected patent ductus arteriosus (PDA), primarily using transthoracic echocardiography (TTE) to illustrate the imaging characteristics. This patient had been referred to our institution for an abnormal electrocardiogram, and TTE subsequently (Figure 1) revealed a dilated left ventricle with moderately to severely reduced function; LV ejection fraction was 30% by two- and three-dimensional quantification. The left ventricle had a spherical appearance with a thin-walled, truncated, and akinetic distal LV. The right ventricle appeared elongated and was noted to wrap around the distal left ventricle, but right ventricular systolic function was normal. There were no significant valvular abnormalities, and no evidence of residual PDA flow. Subsequent cardiac magnetic resonance (CMR) imaging confirmed these findings (Figure 1). The TTE and CMR findings seen in this patient are consistent with LV apical hypoplasia. Until now, this cardiomyopathy has been described only as an isolated congenital anomaly primarily using CMR and cardiac computed tomography. To our knowledge, this is the first reported case of LV apical hypoplasia in conjunction with another congenital cardiac abnormality, and the findings demonstrate that the distinctive appearance of this cardiomyopathy can be easily identified with echocardiography. As more cases are recognized and patients are followed over time, the natural history and optimal treatment for this cardiomyopathy may be further elucidated.

Predictors of preserved left ventricular systolic function after surgery for chronic organic mitral regurgitation: a prospective study.

BACKGROUND AND AIM OF THE STUDY: For patients with chronic severe mitral regurgitation (MR), one consideration for the timing of mitral valve surgery is the desire to have a preserved postoperative left ventricular ejection fraction (LVEF). It was hypothesized that the preoperative left ventricular (LV) volume and effective forward LVEF (defined as the ratio of forward aortic stroke volume and LV end-diastolic volume (LVEDV)) would accurately predict the intermediate (three-month) LVEF following surgery. It was also hypothesized that at years after successful surgical correction, there would be ongoing positive ventricular remodeling with improvements in systolic function. A quantitative volumetric cardiovascular magnetic resonance (CMR) system was used prospectively to study these relationships, and to define predictors of postoperative LV systolic function after surgery for chronic severe MR. METHODS: Twenty patients (eight females, 12 males; mean age 52 +/-12 years) with chronic severe MR, who had been referred for elective mitral valve repair or replacement with chordal preservation, were prospectively enrolled. All patients underwent quantitative CMR with assessment of LV volume, LVEF, and effective forward LVEF prior to, and at three months after, surgery. Fourteen of the patients returned at a median of 27 months after valve surgery for repeat CMR. RESULTS: The preoperative LVEF was normal in 90% of patients (0.62 +/- 0.09), but the effective forward LVEF was depressed in all subjects (0.36 +/- 0.09). Compared to preoperative values, at three months after surgery the LVEF had declined by 0.16 +/- 0.08 (p < 0.001), whereas the effective forward LVEF was increased by 0.09 +/- 0.10 (p < 0.001) and the LV end-diastolic volume index (LVEDVI) had declined by 32% (p < 0.001). Multivariate analysis demonstrated a significant correlation between postoperative LVEF and both preoperative LV end-systolic volume index (LVESVI) (p = 0.003) and the preoperative effective forward LVEF (p = 0.05). A depressed postoperative LVEF (< 0.50) during the early period was best predicted by a preoperative effective forward LVEF < 0.40 (sensitivity 100%, specificity 75%). At the 27-month follow up, 12 of the 14 patients (86%) had a normal LVEF, and there was a continuing normalization of other LV parameters, including the LVEDVI and LV mass index. CONCLUSION: Among patients with chronic severe MR, the preoperative LVESVI best correlated with the three-month postoperative LVEF. A preoperative effective forward LVEF < 0.40 accurately predicted a depressed postoperative LVEE. Over the succeeding two years, there will be ongoing positive LV remodeling. If confirmed in a larger series, the effective forward LVEF may serve as a useful clinical guide for the timing of corrective surgery in this population.