Left ventricular non-compaction (LVNC) is an increasingly recognised cardiomyopathy with a variable clinical presentation. The perioperative implications of this condition are unknown. This retrospective study examined post-operative complications in a cohort of patients with LVNC undergoing a variety of surgical interventions.
First reported at autopsy in 1932, LVNC describes a condition characterised by prominent trabeculations separated by deep recesses in the same segments of the left ventricular myocardium. Often the affected myocardial segments are hypocontractile and display a two-layer appearance with a thicker, ‘non-compacted’ or hypertrabeculated layer on the endocardial side and a thinner, ‘compacted’ layer on the epicardial side (Figs 1 and 2). Involvement of the entire left ventricular myocardium is rare and typical changes of LVNC are most often noted in the apex as well as the inferior and lateral walls at the mid-ventricular level.1 The observation that basal left ventricular segments are less often involved may reflect the fact that during foetal development, the condensation of loose trabecular fibres and spaces to produce normal, compacted myocardium proceeds from base to apex.1 Some authors postulate that arrest of the condensation process, which is completed by the fifth to eighth gestational week, results in LVNC.2 However, the arrest of normal intrauterine development fails to explain the fact that some cases are acquired3 and multiple instances have been reported in which infants were found to have LVNC, even though prior foetal echocardiography did not demonstrate this abnormality.4
Since 1995, the WHO has considered LVNC to be an unclassified cardiomyopathy.5 In 2006, a working group of the American Heart Association (AHA) classified LVNC as a primary cardiomyopathy (i.e. the heart is the predominant organ involved in the condition) of genetic origin.6 The AHA scientific statement acknowledges that both familial and non-familial cases exist and that the results of genetic testing in affected individuals are heterogeneous. Others report a rate of familial involvement ranging from 18 to 33%2 and the Heart Failure Society of America recommends screening first-degree relatives for the condition.7 In children, a variety of congenital cardiac anomalies have been reported together with the finding of non-compacted left ventricular segments, including atrial and ventricular septal defects, aortic coarctation and aortic stenosis.8 Although classified by the AHA as a primary cardiomyopathy, LVNC has been described in association with extracardiac conditions, most notably neuromuscular disorders.9,10 The frequency with which neuromuscular disease occurs in LVNC varies considerably and depends on the population studied (children or adults) and the criteria used to establish the diagnosis of LVNC.
Earlier studies estimated the prevalence of LVNC to be between 0.014 and 0.24% depending on the population studied.2 More recently, Stanton et al.11 found isolated LVNC (not associated with other congenital heart disease) in 0.02% of 141 047 patients who were at least 16 years of age. In contrast, Kohli et al.12 recently reported that 23.6% of 199 patients referred to a heart failure clinic satisfied at least one set of echocardiographic criteria for LVNC, as did 8% of healthy controls. It is possible that as awareness of the condition increases among echocardiographers, the reported prevalence will rise.13 The condition has been discovered in utero, but in one patient the diagnosis was made at the age of 94 years.2 Along with increased awareness, improvements in imaging resolution may also contribute to an increase in the number of reported cases. A search of the PubMed database accessed on 21 March 2010, using the term ‘noncompaction’, yielded 115 results for the year 2009 alone (http://www.ncbi.nlm.nih.gov/pubmed). This same search performed for the year 2000 yielded only eight results. Despite the increased recognition of the condition, very few reports have described the perioperative outcomes of patients with LVNC.
Ethical approval for this study (IRB#: 08-007074) was provided by the Mayo Clinic Institutional Review Board of Mayo Clinic Hospitals, Rochester, Minnesota, USA (Chairperson, J. Lobl) on 28 October 2008. After obtaining Institutional Review Board approval and patient consent, all patients with an echocardiographic diagnosis of LVNC who underwent a procedure at the Mayo Clinic Rochester from 1 January 2001 to 31 December 2008 were identified by retrospective interrogation of the Mayo Clinic Life Science System (MCLSS) data repository. All clinical notes from 1 January 2001 to 31 December 2008 were interrogated using the search terms: ‘non-compaction’, ‘non compaction’, ‘noncompaction’, and ‘hypertrabeculation’. A second interrogation was performed of the Mayo Clinic's echocardiography database within the same time range using the same search terms. The data generated from these two queries were cross-referenced with the anaesthesia database to identify which patients underwent procedures requiring an anaesthetic at Mayo Clinic Rochester during the study period.
Each patient's medical record was manually reviewed. All echocardiographic reports were reviewed for the term ‘non-compaction’ recorded in the ‘impression’ or ‘diagnosis’ sections. Cardiology clinic notes were also reviewed for ‘non-compaction’ as a listed diagnosis. The original echocardiographic images were not viewed and the specific set of criteria used to establish the diagnosis was not recorded. Ejection fraction at the time of diagnosis was recorded. Patient demographics, including sex and age at the time of procedure were recorded. The type of surgery and intraoperative anaesthetic technique(s) were documented. Intraoperative anaesthetic techniques were defined as general anaesthesia, regional anaesthesia, combined general/regional anaesthesia or monitored anaesthesia care (sedation).
Our primary outcome was the presence of any peri-operative complication occurring in the first 7 days following a procedure. For all patients who experienced a complication during this time period, the circumstances surrounding the event were documented, including the characteristics, treatment and clinical course. Information pertaining to the complications was derived from anaesthetic records, post-anaesthesia care unit notes, daily hospital progress notes, consultation notes and hospital follow-up notes. On the basis of review of the chart, the degree of recovery was documented as full, partial or none at the time of the last documented follow-up. The frequency of complications based on ejection fraction at the time of diagnosis was analysed using an exact binomial test. No other statistics were used, as this was a descriptive study.
During the study period, 60 (34 female and 26 male) patients with LVNC underwent 220 procedures. Nineteen patients experienced a total of 25 complications, of which eight were procedurally related (e.g. access site haematoma, surgical site infection) and considered unrelated to LVNC. These were excluded from further analysis. Of the remaining 17 complications (in 15 patients), there were 10 new arrhythmias, five respiratory complications (three patients with pneumonia, two patients with respiratory failure), one seizure and one episode of syncope. Nearly half (47%) of the complications occurred following open cardiac surgery with cardiopulmonary bypass. The remaining complications occurred after interventional cardiac, general surgical, obstetric, neurological or urological procedures (Table 1).
All complications occurred in procedures performed under general anaesthesia (Table 2). The most common complication was post-operative cardiac arrhythmia (10/17). The incidence of new post-operative arrhythmia was 21% (four of 19) after open cardiac procedures. By comparison, the incidence of new post-operative arrhythmia was 3% (six of 201) following non-cardiotomy procedures. Both atrial and ventricular arrhythmias were noted. Electrical cardioversion was used to treat four patients with sustained or symptomatic arrhythmias, whereas one patient required defibrillation for ventricular fibrillation. Two of these patients ultimately required insertion of an automatic implanted cardiac defibrillator (AICD) and one patient had a permanent pacemaker inserted for complete heart block (Table 3). All complications were followed until stabilisation or resolution. The patient's initial presenting ejection fraction was not statistically correlated (P = 0.72) to the number of complications (Table 4). There was no long-term morbidity related to the complications and no perioperative mortality.
A growing awareness of LVNC together with the widespread use of high-resolution, non-invasive imaging such as echocardiography and magnetic resonance imaging has led to a recent increase in publications related to this diagnosis. However, considerable controversy exists in the literature regarding the criteria used to diagnose LVNC. Some authors consider the condition to be present if more than three prominent left ventricular trabeculations are seen distal to papillary muscles in a single echocardiographic imaging plane; these authors also use the term ‘hypertrabeculation’ interchangeably with ‘non-compaction’.14 Some diagnose LVNC when typical two-layer myocardium is identified and the non-compacted layer is at least twice as thick as the compacted layer at end-systole.15 Others have observed that ratios of thickness between non-compacted and compacted myocardium are completely arbitrary and have no patho-anatomical basis.16 These authors suggest that the presence of a two-layer myocardium containing some portion of spongy or non-compacted elements is sufficient alone to establish the presence of LVNC. In the current investigation, patients were identified by performing a database search using both the terms ‘hypertrabeculation’ and ‘non-compaction’, as these terms are used interchangeably by some authors. We did not review the original echocardiographic images to determine what criteria were used to establish the diagnosis of LVNC because no universally accepted set of diagnostic criteria exists.
The clinical course of patients with LVNC is highly variable. Affected patients may present with heart failure requiring insertion of a ventricular assist device or cardiac transplantation.17,18 Some physicians believe that left ventricular hypertrabeculation may develop in patients with heart failure as an adaptive response to left ventricular dilation.19 Acquired cases of LVNC have been described and the formation of prominent trabeculations may represent an attempt to increase endocardial surface area and improve stroke volume.19 Interestingly, the findings of LVNC were noted to regress in one patient in association with an increase in ejection fraction following the institution of biventricular pacing.19 It is also possible that the typical findings of LVNC become visible in some patients only after the left ventricular dilates. Although left ventricular dilatation and reduced ejection fraction have been reported in more than half of LVNC cases, other patients remain asymptomatic and have normal left ventricular systolic function.13 In the current study, 73% of LVNC patients had reduced left ventricular systolic function while the ejection fraction was normal in the remaining 27%.
The reported incidence of atrial fibrillation in LVNC patients is 7–26%, whereas ventricular arrhythmias have been noted to occur in 6–62% of cases.2 New-onset arrhythmia accounted for 10 of the 17 post-operative complications observed in the current study population. The 21% incidence of new post-operative arrhythmia following open cardiac surgical procedures in the present investigation is comparable with the reported range of 25–50% following heart surgery in other populations.20 A recent study from our institution reported an incidence of atrial fibrillation of 21% following cardiac surgery.21 Similarly, the 3% incidence of arrhythmia noted after non-cardiotomy procedures is well within the range (0.37–20%) reported for other groups of patients.22 The overall incidence of arrhythmias in patients with LVNC probably does not differ from that in other surgical patients with similar degrees of ventricular dysfunction undergoing similar procedures.2
Some authors have suggested that the presence of non-compacted myocardium may increase the risk of thromboembolism, although this assertion is not supported by the literature.2,23 Although the presence of non-compacted myocardium alone does not seem to increase the risk of thromboembolism, many clinicians prescribe anticoagulants for LVNC patients who develop atrial fibrillation, particularly when the ejection fraction is also depressed.2,23 Ninios et al.18 reported thrombosis of an axial flow ventricular assist device in a patient with LVNC, although levels of anticoagulation in that patient were variable and it is not clear that this complication was related to the presence of non-compacted myocardium. In the current study, one patient suffered a seizure, whereas another experienced a syncopal episode. However, no demonstrable cases of thromboembolic disease occurred in any patient.
Post-operative respiratory complications were noted in five patients. Two infants required tracheal intubation for respiratory failure following cardiovascular surgery. Two patients developed post-operative pneumonia, which required antibiotic treatment and another patient with dialysis-dependent renal failure developed pulmonary oedema. The post-operative respiratory complication rate of 1.5% following non-cardiac surgery is similar to that in other reported patients following non-thoracic surgery (2.7%).24 The relatively large number of non-cardiac operations performed without general anaesthesia in this study may have reduced the incidence of post-operative respiratory complications. The post-operative respiratory complication rate of 11% following cardiac surgery is similar to that following cardiac surgery in other studies (7–12%).25,26 The 5% incidence of pneumonia following cardiac surgery is also similar to previous reports.27,28 In comparison, a recent study of patients who had undergone thoracic surgery at our institution found a 9.3% incidence of post-operative respiratory failure requiring prolonged ventilatory support and a 7.3% incidence of post-operative pneumonia.29
The overall incidence of post-operative complications in this study was low. Non-procedural complications occurred after 7.7% (17 of 220) of interventions and almost half of these followed open cardiac surgery performed with general anaesthesia. Although no control group was used, the type and incidence of complications encountered after cardiac surgery were typical of those reported in the literature for populations of cardiac surgical patients in general. Interestingly, no post-operative complications were recorded following procedures performed with regional anaesthesia or monitored anaesthesia care (sedation), even though the latter accounted for a large percentage of the interventional cardiology procedures. Additionally, all post-operative complications either resolved or were treated successfully and no patient died.
To our knowledge, this is the first study to report post-operative outcomes in patients with LVNC. Although the literature contains case reports of LVNC, very few have described perioperative events in these patients and none of these reports focused on post-operative complications.3,17,18 Errando et al.30 described the anaesthetic management of a patient with LVNC who required emergency splenectomy following trauma. Post-operatively, the patient's implanted defibrillator discharged once in response to ventricular tachycardia, although there was no apparent clinical deterioration noted at that time.
The results of our study suggest that the rate of post-operative complications in patients with LVNC is similar to the incidence in those without LVNC. Therefore, the presence of non-compacted myocardium alone does not seem to confer any additional perioperative risk. Instead, anaesthesiologists should recognise that many patients with LVNC suffer from reduced ejection fraction and heart failure. However, because LVNC is clinically heterogeneous and some patients are asymptomatic, the pre-operative evaluation should focus on determining the presence or absence of heart failure and the adequacy of current medical management. Although the current study showed no post-operative complications in patients who received monitored anaesthesia care or regional anaesthesia, the selection of general anaesthesia is often dictated by the operative procedure. Because of the sample size and lack of standardisation in this retrospective, observational study, we cannot recommend any particular general anaesthetic agent. Similarly, the selection of any specific monitoring technique is probably best tailored to the physiological status of the patient and the nature of the procedure rather than the presence of LVNC.
In summary, the incidence of post-operative complications among patients with LVNC who underwent a variety of surgical procedures was low and similar to reported complication rates in other patients with similar degrees of ventricular dysfunction.
There was no financial support or sponsorship for this study.
H.P.S., S.L.K., S.R.R. and K.H.R. have seen the original study data, reviewed the analysis of the data, approved the final manuscript and are the authors responsible for archiving the study files.
H.P.S., S.L.K., S.R.R. and K.H.R. reported no conflicts of interest.
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