Laila Hellgren

Improved early results after heart valve surgery over the last decade

OBJECTIVES This study was undertaken to investigate time trends in early mortality, morbidity and clinical characteristics of patients undergoing heart valve surgery over the last decade. METHODS A regional, prospectively collected, study comprising all patients (2,327) undergoing valve surgery in a defined geographical area from January 1990 to December 1999 was conducted. Data were collected from 1,746 patients submitted to aortic valve replacement (AVR), 432 to mitral valve replacement (MVR), 78 to double valve replacement (DVR) and 71 to mitral valve repairs. Logistic regression was used to identify risk factors for early mortality. Time trends of early mortality, morbidity and clinical characteristics were analysed. RESULTS The total early mortality rate was 5.9%; for AVR it was 4.8%, MVR 9%, DVR 14% and mitral valve repair 1.4%. The risk factor profiles for early mortality were similar in all groups of valve interventions, with shock, age over 70 years and advanced NYHA class as the strongest risk factors. There was a decrease in early mortality over the period which remained after correction for risk factors. The proportion of patients over 70 years of age and of patients with diabetes increased, whereas other risk factors were not altered during the study period. CONCLUSION It is confirmed that early risks for death after heart valve surgery have decreased. This improvement was consistent after adjustment for risk factors.

Prediction of postoperative atrial fibrillation in a large coronary artery bypass grafting cohort

The objective of this study was to identify and evaluate predictors of postoperative atrial fibrillation (POAF) in a large coronary artery bypass grafting (CABG) cohort. This was a single centre study of 7115 consecutive patients with preoperative sinus rhythm who underwent isolated CABG between January 1996 and December 2009. Independent risk factors for POAF were identified with multiple logistic regression. The predictive quality of the final model was evaluated by comparing predicted and observed events of POAF, in an effort to find patients at high risk of developing POAF. After CABG, 2270 patients (32%) developed POAF during hospital stay. Independent risk factors of POAF included advancing age (odds ratio, OR 2.0-7.3), preoperative S-creatinine ≥ 150 µmol/l (OR 1.6), male gender (OR 1.2), New York Heart Association class III/IV (OR, 1.2), smoking (OR 1.1), prior myocardial infarction (OR 1.1) and absence of hyperlipidemia (OR 0.9). The final prediction model was moderate (area under curve, 0.62; 95% confidence interval, 0.61-0.64). Patients with POAF had more postoperative complications, including a higher incidence of stroke and increased length of hospital stay. In conclusion, several risk factors for POAF were identified, but the moderate value of the prediction model confirms the difficulty of identifying patients at high risk of developing POAF after CABG.

Experience with the Impella® recovery axial-flow system for acute heart failure at three cardiothoracic centers in Sweden

Objectives. The Impella® recovery axial-flow system is a mechanical assist system for use in acute heart failure. This retrospective study reports the use of the device at three cardiothoracic units in Sweden. Design. Fifty patients (35 men, mean age 55.8 years, range 26 to 84 years) underwent implantation of 26 Impella®LP 2.5/5.0 (support-time 0.1 to 14 days), 16 Impella®LD (support-time 1 to 7 days) and 8 Impella®RD (support-time 0.1 to 8 days) between 2003 and 2007. Implantation was performed because of postcardiotomy heart failure (surgical group, n=33) or for various states of heart failure in cardiological patients (non-surgical group, n=17). The intention for the treatments was mainly to use the pump as a ”bridge-to-recovery”. Results. Early mortality in the surgical and non-surgical groups was 45% and 23%, respectively. Complications included infection, 36% and right ventricular failure, 28%. Cardiac output and cardiac power output postoperatively were significantly higher among survivors than non-survivors. Conclusions. The Impella® recovery axial-flow system facilitates treatment in acute heart failure. Early intervention in patients with acute heart failure and optimized hemodynamics in the post-implantation period seem to be of importance for long-term survival. Insufficient early response to therapy should urge to consider further treatment options.

Postoperative atrial fibrillation predicts cause-specific late mortality after coronary surgery

Abstract Objectives. To investigate the association between postoperative atrial fibrillation (POAF) and cause-specific death after coronary artery bypass grafting (CABG) over time. Design. The cohort included 6821 patients undergoing primary isolated CABG between 1996 and 2009. Survival analyses using Cox proportional hazards determined the association between POAF and late mortality and cause of death. Four categories of mortality were examined: cardiac mortality; and death related to arrhythmia, cerebrovascular disease, and heart failure. Results. Median follow-up was 9.8 years and 2152 of 6821 patients (32%) developed POAF. During follow-up, 2302 of 6821 patients (34%) died. For all mortality categories, lower survival rates were found among POAF patients. After adjustment for baseline characteristics, medical history, and preoperative status, POAF was related to increased mortality in all four categories: cardiac mortality (HR 1.4; 95% CI 1.3–1.5); death related to arrhythmia (HR 1.8; 95% CI 1.6–2.0); cerebrovascular disease (HR 1.4; 95% CI 1.2–1.6); and heart failure (HR 1.4; 95% CI 1.3–1.6). The effect remained more than 8 years after surgery. Conclusions. POAF predicts cause-specific late mortality after CABG, with a sustained effect many years postoperatively. This suggests that POAF-episodes are not merely an indication of more advanced disease at surgery, but predicts a persistent negative effect on cause-specific survival.

A modified Glenn shunt improves haemodynamics in acute right ventricular failure in an experimental model

OBJECTIVES Right heart failure is a major cause of morbidity and mortality after left ventricular assist device implantation and is still hard to predict. This study investigated the haemodynamic effect of a modified Glenn shunt on induced right ventricular (RV) failure. METHODS Isolated RV failure was induced by coronary ligation in 11 pigs. A modified Glenn shunt was established by a superior vena cava to pulmonary artery connection. Haemodynamic data were obtained at baseline, RV failure, and RV failure and open shunt. Myocardial biopsies were taken to ascertain established heart failure. RESULTS RV failure defined as right atrial pressure ≥20 mmHg was achieved in all 11 animals. A reduction in cardiac output (CO) from 3.7 (3.5-4.2) to 2.3 l/min (2.0-2.6) and mean arterial pressure (MAP) from median 72.7 (70.1-82.2) to 55.9 mmHg (52.6-59.8) was seen during heart failure. The median flow in the shunt was 681 ml. Right atrial pressures decreased from 20.3 (19.6-21.1) to 13.4 mmHg (12.7-14.0), and RV pressures decreased from 18.1 (16.4-20.1) to 13.6 mmHg (13.5-14.2) with open shunt (P = 0.001 for both). CO increased to 2.9 l/min (2.4-3.3) when the shunt was in use. Mixed venous oxygen saturation increased with the shunt from 32 (27-38) to 49% (45-56), P = 0.001. Genes associated with heart failure were upregulated during heart failure. CONCLUSIONS A modified Glenn shunt improved haemodynamics by reduced right atrial pressure, increased CO, MAP and mixed venous oxygen saturation in an experimental model of induced RV failure.

Severe mitral regurgitation--relations between magnetic resonance imaging, echocardiography and natriuretic peptides

Background. Assessment of the severity of mitral regurgitation by echocardiography can be technically demanding in certain patients and supplementary methods are therefore desirable. This study addressed the agreement between magnetic resonance imaging (MRI) and echocardiography, and their relations to natriuretic peptides (NT-proANP and NT-proBNP), in quantifying severe mitral regurgitation. Methods. Eighteen patients with severe mitral regurgitation scheduled for surgery underwent MRI, echocardiography and assay of natriuretic peptides preoperatively for clinical assessment. Results. MRI and echocardiography were comparable in measuring severity of regurgitation qualitatively but not quantitatively, mitral regurgitant fraction (mean difference 27.5 (11) ml). There was a correlation between increasing regurgitant fraction on MRI and increased levels of plasma NT-proANP and NT-proBNP. In echocardiography, increasing vena contracta width and increasing PISA correlated to increased levels of plasma NT-proANP and NT-proBNP. No other correlation was found between measures on MRI and echocardiography and natriuretic peptides. Conclusions. MRI and echocardiography were comparable grading the severity of mitral regurgitation with qualitative measures but not with quantitative measures. MRI might be a complement to echocardiography when a more distinct measure of the regurgitant volume is needed, as in paravalvular leakage.

High incidence of atrial fibrillation after coronary surgery

OBJECTIVES Postoperative atrial fibrillation (POAF) affects a third of all patients after coronary artery bypass surgery (CABG), but short-term follow-up of heart rhythm after discharge has been sporadic and shown varied results. The aim of this study was to examine the incidence of post-discharge atrial fibrillation (AF) for 30 days following hospital discharge after CABG. METHODS A total of 67 patients, 19 (28%) with POAF during the initial hospitalization and 48 (72%) without POAF were included. Patients recorded intermittent electrocardiogram registrations three times daily, and additionally in case of arrhythmia symptoms. Presence of post-discharge AF was compared between the groups. All patients were in sinus rhythm at discharge. RESULTS Twenty of 67 patients (30%) were diagnosed with post-discharge AF. Overall, 35% of them were entirely asymptomatic. POAF patients had a higher incidence of post-discharge AF (11 of 19, 58%) than non-POAF patients (9 of 48, 19%), with six times the odds of developing post-discharge AF compared with non-POAF patients [odds ratio (OR) 6.0; 95% CI 1.9-19, P = 0.002]. Patients with POAF registered episodes of post-discharge AF earlier during the follow-up period (mean Day 3 after discharge, range 1-9 days) than non-POAF patients (Day 10, range 7-14 days, P < 0.001). CONCLUSIONS A high incidence of both symptomatic and asymptomatic AF was recorded during 30 days following hospital discharge after CABG. The incidence was highest among patients with POAF, of whom more than half experienced post-discharge AF.

Experimental Venoarterial Extracorporeal Membrane Oxygenation Induces Left Ventricular Dysfunction.

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) has experienced an increased use in acute cardiac failure. There are some reports on negative effects of VA-ECMO on cardiac function, such as left ventricular (LV) dilatation and cardiac stun, but the support in the literature is scarce. This study investigates the effects of experimental VA-ECMO on LV function in both peripheral and central cannulation. Ten pigs were randomized to VA-ECMO by either peripheral cannulation through the femoral vessels or central cannulation in the right atrium and ascending aorta. Left ventricular performance was measured with pressure-volume catheters during 5 hours of VA-ECMO. The LV end-diastolic and end-systolic volumes increased comparably in both groups during ECMO. Left ventricular ejection fraction, stroke work, and maximum rate of pressure change decreased comparably in both groups as a function of time on ECMO. The site of cannulation had no impact on the LV response to ECMO. In conclusion, VA-ECMO increased LV volumes and reduced LV function, irrespective of cannulation site in this experimental model. Reduced LV ejection fraction and stroke work indicated LV dysfunction during ECMO.

Cavoaortic shunt improves hemodynamics with preserved oxygen delivery in experimental right ventricular failure during left ventricular assist device therapy

OBJECTIVE Right heart failure is a major cause of morbidity and mortality after left ventricular assist device (LVAD) implantation. This study evaluated the approach of a cavoaortic shunt included in the LVAD circuit, which would aim to relieve venous congestion and improve hemodynamics with preserved oxygen delivery during induced right ventricular failure. METHODS Right ventricular failure was induced by coronary ligation in 10 pigs. An LVAD was implanted and a cavoaortic shunt was created from the right atrium and included in the assist circuit. Hemodynamic measures and blood gas analyses were analyzed. Oxygen delivery and oxygen consumption were estimated. RESULTS Right atrial pressure decreased from more than 20 mm Hg to 17.2 mm Hg (14.8-18.4) with the LVAD and to 14.1 mm Hg (11.2-15.5) (P < .01) with the LVAD and cavoaortic shunt. Mean arterial pressure increased from 70.9 mm Hg (67.6-79.8) to 81.5 mm Hg (70.8-92.6) (P = .02) with addition of the shunt into the assist circuit. Cardiac output increased from 3.5 L/min (2.6-4.2) to 4.9 L/min (3.5-5.6) (P < .01) with cavoaortic shunting. Oxygen delivery with the cavoaortic shunt was 337 mL/min (± 70) as compared with left ventricular assist alone at 258 mL/min (± 52) (P < .01). Oxygen consumption was restored during use of the cavoaortic shunt. CONCLUSIONS A cavoaortic shunt combined with an LVAD during right ventricular failure reduces central venous pressures, increases systemic arterial pressure, and enables increased cardiac output compared with device therapy alone. This was feasible with preserved oxygen delivery.

Preoperative Brain Natriuretic Peptide Predicts Late Mortality and Functional Class but Not Hospital Readmission After Cardiac Surgery

OBJECTIVES N-terminal brain natriuretic peptide (NT-proBNP) is an established biomarker of heart failure and has been found to predict mortality and morbidity after cardiac surgery. The aim of this study was to investigate whether preoperative NT-proBNP can predict postoperative New York Heart Association (NYHA) functional class and hospital readmission in addition to morbidity and mortality. DESIGN Retrospective. SETTING University hospital. PARTICIPANTS All patients undergoing aortic valve replacement for aortic stenosis and coronary artery bypass grafting from January to December 2008 (n = 390). MEASUREMENTS AND MAIN RESULTS Preoperative NT-proBNP was recorded prospectively. Five-year mortality was obtained through national registries. Postoperative functional class, morbidity, and hospital readmission were obtained through telephone interviews. Patients were divided into quartiles based on preoperative NT-proBNP; the medians of each quartile were 103 ng/L, 291 ng/L, 825 ng/L and 2,375 ng/L. Increased preoperative NT-proBNP was associated with reduced postoperative functional class. In the first quartile, 7% (7/97) were in NYHA functional class III-IV compared to 26% (25/97) in the fourth quartile (p<0.01). Increased preoperative NT-proBNP was also associated with reduced long-term survival (p<0.01). The covariate adjusted hazard ratio for mortality in the fourth quartile was 2.9 (1.61-5.08; p<0.01) compared to the other quartiles. No association was found between preoperative NT-proBNP and postoperative hospital readmission. CONCLUSIONS Increased preoperative NT-proBNP is associated with reduced long-term survival and functional class but not hospital readmission post-cardiac surgery. Thus, NT-proBNP might have additive value to established risk factors in the preoperative assessment of patients undergoing cardiac surgery.