Cardiac troponin release following coronary artery bypass grafting: mechanisms and clinical implications

The use of biomarkers is undisputed in the diagnosis of primary myocardial infarction (MI), but their value for identifying MI is less well studied in the postoperative phase following coronary artery bypass grafting (CABG). To identify patients with periprocedural MI (PMI), several conflicting definitions of PMI have been proposed, relying either on cardiac troponin (cTn) or the MB isoenzyme of creatine kinase, with or without supporting evidence of ischaemia. However, CABG inherently induces the release of cardiac biomarkers, as reflected by significant cTn concentrations in patients with uncomplicated postoperative courses. Still, the underlying (patho)physiological release mechanisms of cTn are incompletely understood, complicating adequate interpretation of postoperative increases in cTn concentrations. Therefore, the aim of the current review is to present these potential underlying mechanisms of cTn release in general, and following CABG in particular (Graphical Abstract). Based on these mechanisms, dissimilarities in the release of cTnI and cTnT are discussed, with potentially important implications for clinical practice. Consequently, currently proposed cTn biomarker cut-offs by the prevailing definitions of PMI might warrant re-assessment, with differentiation in cut-offs for the separate available assays and surgical strategies. To resolve these issues, future prospective studies are warranted to determine the prognostic influence of biomarker release in general and PMI in particular.

The evolution of arch surgery: Frozen elephant trunk or conventional elephant trunk?

Treatment of aortic arch aneurysms and dissections require highly complex surgical procedures with devastating complications and mortality rates. Currently, repair of the complete arch until the proximal descending thoracic aorta consists of a two-stage procedure, called elephant trunk (ET) technique, or a single stage a single-stage technique referred to as frozen elephant trunk (FET). There is conflicting evidence about the perioperative results of ET in comparison with FET. We carried out a meta-analysis to investigate possible differences in perioperative and early (up to 30 days) outcomes of ET vs. FET, particularly for mortality, spinal cord injury (SCI), stroke, and renal failure. We also performed a meta-regression to explore the effects of age and sex as possible cofactors. Twenty-one studies containing data from interventions conducted between 1997 and 2019 and published between 2008 and 2021 with 3153 patients (68.5% male) were included. ET was applied to 1,693 patients (53.7%) and FET to 1460 (46.3%). Overall mortality after ET was 250/1693 (14.8%) and after FET 116/1460 (7.9%). Relative risk (RR) and 95% confidence interval (CI) were 1.37 [1.04 to 1.81], p = 0.027. There was no significant effect of age and sex. SCI occurrence after the second stage of ET was 45/1693 (2.7%) and after FET 70/1,460 patients (4.8%) RR 0.53 [0.35 to 0.81], p = 0.004. Age and sex were not associated with the risk of SCI. No significant differences were observed between ET and FET in the incidence of stroke and renal failure. Our results indicate that ET is associated with higher early mortality but lower incidence of SCI compared to FET. When studies published in the last 5 years were analyzed, no significant differences in mortality or SCI were found between ET and FET. This difference is attributed to a decrease in mortality after ET, as the mortality after FET did not change significantly over time.

Timing of pulmonary valve replacement in patients with corrected Fallot to prevent QRS prolongation

OBJECTIVES

Timing of pulmonary valve replacement (PVR) remains one of the most heavily debated topics in congenital cardiac surgery. We aimed to analyse the temporal evolution of QRS duration before and after PVR.

METHODS

We included 158 consecutive patients who underwent PVR after previous correction with transannular patch. All 3549 available serial standard 12-lead surface QRS measurements of 158 (100%) patients were analysed with linear mixed-effect modelling.

RESULTS

PVR was performed at a mean age of 28.0 ± 10.7 years, 23.4 ± 8.4 years after correction. Hospital survival was 98.1%. A longer time interval between ToF correction and PVR (P < 0.001), and an older age at correction (P = 0.015) were predictive of progressive QRS prolongation after PVR. Women on average had a shorter QRS duration (P = 0.005) after PVR. The model predicted that in patients corrected early (model age 0.5 years), PVR within 17 years after correction leads to narrowing or stabilization of QRS width. PVR beyond 17 years was associated with prolongation of QRS duration. In a patient corrected late (model age 5 years), PVR has to be performed within 15 years after correction to prevent prolongation. Finally, a longer time period between correction and PVR was associated with an increased hazard of cardiac death (hazard ratio 1.097, 95% confidence interval 1.002–1.200).

CONCLUSIONS

Prolongation of QRS duration after PVR was associated with a longer time between correction and PVR, older age at correction and male sex. Prevention of progressive QRS prolongation by earlier PVR can potentially reduce the hazard of adverse events after PVR.

Long-term Clinical and Echocardiographic Outcomes in Young and Middle-aged Adults Undergoing the Ross Procedure

Importance

There is no ideal valve substitute for young adults requiring aortic valve replacement. Multicenter data supporting use of the Ross procedure with respect to long-term postoperative valve-related mortality and reintervention, as well as function of the autograft and pulmonary homograft, are needed.

Objective

To determine the long-term clinical and echocardiographic outcomes in young and middle-aged patients undergoing the Ross procedure.

Design, Setting, and Participants

A retrospective multicenter international cohort study with a median follow-up period of 9.2 years was conducted in 5 experienced centers regularly performing the Ross procedure. Consecutive patients aged 18 to 65 years were included by each center between 1991 and 2018.

Main Outcomes and Measures

Survival and autograft-related and homograft-related reintervention. Serial echocardiographic measurements of valve function were analyzed using mixed-effects modeling.

Results

During the study period, 1431 patients (74.3% men; n = 1063) were operated on at a median age of 48.5 years (mean [SD], 47.7 [9.5]; range, 18.1-65; interquartile range, 42.7-54.0). Implantation techniques were root inclusion in 355 (24.9%), root replacement in 485 (34.0%), and subcoronary implantation in 587 (41.1%). Right ventricular outflow tract reconstruction was performed with homografts in 98.6% (n = 1189) and bioprostheses in 1.4% (n = 17). Ten patients (0.7%) died before discharge. Median follow-up was 9.2 years (13 015 total patient-years). Survival after 10 and 15 years was 95.1% (95% CI, 93.8%-96.5%) and 88.5% (95% CI, 85.9%-91.1%), respectively. Freedom from autograft and homograft reintervention after 15 years was 92.0% and 97.2%, respectively. Late events were autograft endocarditis in 14 patients (0.11% per patient-year), homograft endocarditis in 11 patients (0.08% per patient-year), and stroke in 37 patients (0.3% per patient-year).

Conclusions and Relevance

Given its excellent short-term and long-term outcome in young and middle-aged adults in this study, the Ross procedure should be considered in young and middle-aged adults who require aortic valve replacement. Patients should be referred to an experienced center with a program dedicated to the Ross procedure.

Long-term clinical outcome and echocardiographic function of homografts in the right ventricular outflow tract†

OBJECTIVES

Although homografts are often the preferred valve conduits for right ventricular outflow tract (RVOT) reconstruction, data on long-term homograft-related outcomes, durability and impact on quality of life (QoL) are scarce. The aim of this study was therefore to describe the long-term homograft function, clinical outcomes and QoL after RVOT reconstruction.

METHODS

We performed a single-centre retrospective analysis of all consecutive patients who underwent RVOT reconstruction with a homograft. Multiple subsequent allografts in the same patients were regarded as separate subjects. Valve-related events were analysed by Kaplan-Meier and Life Table methods. Serial echocardiographic measurements were analysed with mixed effects models. In addition, QoL was repeatedly assessed and compared with a matched general population.

RESULTS

In total, 701 consecutive homografts were implanted in 604 patients [59.6% males, mean age at operation 19.5 ± 15.2 (standard deviation)]. Hospital mortality was 3.3%. After 25 years follow-up, survival and freedom from valve replacement were 84 ± 4% and 56 ± 6%, respectively. Freedom from valve replacement after 15 years for patients under 1 year of age was 28 ± 14% years, for those between 1 and 18 years, 59 ± 8%, and for those older than 18 years, 82 ± 5%. The peak gradient increased predominantly in the first postoperative decade in infants and paediatric patients from 19 to 54 mmHg. In adults, the average gradient increased from 9 to 31 mmHg after 14 years. Compared to a gender- and age-matched Dutch population, patients reported lower vitality and general health but less bodily pain. Patients, in whom QoL was repeatedly assessed, reported lower scores on physical functioning and vitality after a 5-year follow-up period. However, we found no differences in any of the subscales in patients who underwent valve replacement during the 5-year interval.

CONCLUSIONS

Homografts are a durable valve alternative for RVOT reconstruction; in particular, adults show extensive freedom from valve replacement and report QoL comparable with healthy subjects. An online interactive application form created by our institution can be used to assess patient outcome after RVOT reconstruction with a homograft for different patient profiles.

Influence of pregnancy on long-term durability of allografts in right ventricular outflow tract

BACKGROUND

There is very limited published evidence about the influence of pregnancy on allograft durability in right ventricular outflow tract position. We present the first study using mixed and joint modeling.

METHODS

This retrospective study compared clinical and valve related outcomes of all consecutive female hospital survivors in their fertile life phase (18-50 years) based on pregnancy. Serial echocardiographic measurements of pulmonary gradient and regurgitation were analyzed for their association with valve replacement using joint models for longitudinal and time-to-event data. Occurrence of first pregnancy was included as a time-dependent intermediate event in both the longitudinal and survival analyses of the joint model to assess its impact on the hemodynamic and clinical outcome.

RESULTS

In total, 196 consecutive women in their fertile life-phase with an allograft were included. Complete information of 176 (90%) allografts in 165 women was available, including 1395 echocardiograms. Of these women, 51 (30.9%) women had 84 completed pregnancies at an average age of 29.1 ± 3.9 (SD) years; 8.1 ± 6.1 years since allograft implantation. Tetralogy of Fallot was the most common diagnosis in both groups. After a mean follow-up of 15.2 years (range 0.1-30), 7 (13.7%) parous women underwent valve replacement versus 20 (17.5%) nulliparous women. During this follow-up, the mean allograft gradient in parous (24.2 mm Hg) and nulliparous (21.0 mm Hg) women was comparable (P = .225). A 1-mm Hg increase in pulmonary gradient increased the instantaneous risk of pulmonary valve replacement (PVR) by a ratio of 1.051 (P < .001), regardless of pregnancy. Similarly, development of moderate or severe regurgitation increased the risk of PVR (P = .038), regardless of pregnancy. Pregnancy was not associated with a change in the allograft gradient (P = .258), regurgitation grade (P = .774), or hazard of PVR (P = .796) during follow-up.

CONCLUSIONS

Pregnancy is not associated with impaired allograft durability in women with good cardiac health.

Downsized cryopreserved and standard-sized allografts for right ventricular outflow tract reconstruction in children: long-term single-institutional experience

OBJECTIVES

The objective of this study was to determine long-term results with bicuspidalized allografts compared to non-bicuspidalized allografts in children under 2 years undergoing primary correction of the right ventricular outflow tract.

METHODS

Thirty-five consecutive bicuspidalized allografts were compared to 45 consecutive non-bicuspidalized allografts implanted during the same period. Valve-related events were analysed with Kaplan-Meier and Cox-regression techniques. Mixed-effects modelling was used to analyse serial echocardiographic measurements of pulmonary gradient. In addition, a systematic review with meta-analysis of the published literature concerning implantation of bicuspidalized allografts was performed.

RESULTS

Perioperative characteristics and in-hospital mortality [bicuspidalized 5 (14.3%), non-bicuspidalized 6 (13.3%)] were comparable (P = 0.902). Bicuspidalized allografts were smaller (14.7 vs 16.5 mm, P = 0.023) and always (100%) of pulmonary origin compared to 26 (57.8%) of the standard-sized allografts. There were no differences in late mortality between the bicuspidalized and non-bicuspidalized group (6.7% vs 7.7%, P = 0.798) or freedom from allograft replacement at 10 years (82 ± 10% and 71 ± 8%, for bicuspidalized and non-bicuspidalized allografts, respectively). Evolution of peak pulmonary gradient (P = 0.273) was comparable between bicuspidalized and non-bicuspidalized allografts. Meta-analysis showed a pooled early and late mortality for bicuspidalized allograft patients of 10.72% [95% confidence interval (CI) 6.13-18.75] and 1.6% per year (95% CI 0.99-2.79), respectively. Pooled estimated late reintervention and replacement rates were 5.94% per year (95% CI 3.42-10.30) and 3.78% per year (95% CI 2.69-5.32), respectively.

CONCLUSIONS

Bicuspidalization seems to be a viable alternative to combat limited supply of small-sized allografts with acceptable survival and reintervention rates comparable to non-bicuspidalized allografts.