Impact of Myocardial Bridge on Life-Threatening Ventricular Arrhythmia in Patients With Implantable Cardioverter Defibrillator.

Background Myocardial bridge (MB), common anatomic variant, is generally considered benign, while previous studies have shown associations between MB and various cardiovascular pathologies. This study aimed to investigate for the first time possible impact of MB on long-term outcomes in patients with implantable cardioverter defibrillator, focusing on life-threatening ventricular arrhythmia (LTVA). Methods and Results This retrospective analysis included 140 patients with implantable cardioverter defibrillator implantation for primary (n=23) or secondary (n=117) prevention of sudden cardiac death. Angiographically apparent MB was identified on coronary angiography as systolic milking appearance with significant arterial compression. The primary end point was the first episode(s) of LTVA defined as appropriate implantable cardioverter defibrillator treatments (antitachyarrhythmia pacing and/or shock) or sudden cardiac death, assessed for a median of 4.5 (2.2-7.1) years. During the follow-up period, LTVA occurred in 37.9% of patients. Angiographically apparent MB was present in 22.1% of patients; this group showed younger age, lower rates of coronary risk factors and ischemic cardiomyopathy, higher prevalence of vasospastic angina and greater left ventricular ejection fraction compared with those without. Despite its lower risk profiles above, Kaplan-Meier analysis revealed significantly lower event-free rates in patients with versus without angiographically apparent MB. In multivariate analysis, presence of angiographically apparent MB was independently associated with LTVA (hazard ratio, 4.24; 95% CI, 2.39-7.55; P<0.0001). Conclusions Angiographically apparent MB was the independent determinant of LTVA in patients with implantable cardioverter defibrillator. Although further studies will need to confirm our findings, assessment of MB appears to enhance identification of high-risk patients who may benefit from closer follow-up and targeted therapies.

Clinical Outcomes of Myocardial Bridging versus No Myocardial Bridging in Patients with Apical Hypertrophic Cardiomyopathy.

OBJECTIVE: To determine the prevalence and clinical effects of myocardial bridging (MB) in patients with apical hypertrophic cardiomyopathy (AHCM). METHODS: Angiograms from 212 AHCM patients were reviewed to identify MB. The patients were classified into 2 groups: AHCM with and AHCM without MB. We reviewed patient records on cardiovascular (CV) risk factors, symptoms, CV events, and CV mortality. RESULTS: In all, 60 patients with MB and 100 without MB were included. Rates of angina (61.7 vs. 40%; p = 0.008), mimicking non-ST-segment elevation myocardial infarction (15 vs. 3%, p = 0.013), and Canadian Cardiovascular Society class III/IV angina (18.3 vs. 4%; p = 0.003) were higher in patients with MB than in those without. Mean follow-up periods (65.5 ± 50.5 vs. 64.4 ± 43.6 months, p = 0.378) and CV mortality (3.3 vs. 1%; p = 0.652) were similar in the 2 groups. Kaplan-Meier estimates demonstrated that CV event-free survival rates were lower in patients with MB than in those without (71.7 vs. 88%; p = 0.022). MB, late gadolinium enhancement, and female sex were independent risk factors for CV events in a multivariate Cox regression analysis adjusted for other risk factors. CONCLUSION: More serious symptoms and a higher risk of CV events were observed in AHCM patients with MB than in those without MB. CV mortality was similar in these 2 groups.

Myocardial bridging is associated with exercise-induced ventricular arrhythmia and increases in QT dispersion.

BACKGROUND: A myocardial bridge (MB) has been associated with ventricular arrhythmia and sudden death during exercise. QT dispersion (QTd) is a measure of abnormal repolarization and may predict ventricular arrhythmia. We investigated the frequency of ventricular arrhythmias during exercise and the QTd at rest and after exercise, in patients with an MB compared to a normal cohort. METHODS: We studied the rest and stress ECG tracings of patients with an MB suspected by focal septal buckling on exercise echocardiography (EE) (Echo-MB group, N = 510), those with an MB confirmed by another examination (MB group, N = 110), and healthy controls (Control group, N = 198). RESULTS: The frequency of exercise-induced premature ventricular contractions (PVCs) was significantly higher in the Echo-MB and MB groups compared with the Control group (both p < .001). In all, 25 patients (4.9%) in the Echo-MB group, seven patients (6.4%) in the MB group and no patients in the Control group had exercise-induced non-sustained ventricular tachycardia (NSVT). There was no difference in the baseline QTd between the groups. In the Echo-MB and MB groups, QTd postexercise increased significantly when compared with baseline (both p < .001). Patients with NSVT had a higher frequency of male gender and an even greater increase in QTd with exercise compared with the non-NSVT group. DISCUSSION: There is an increased frequency of exercise-induced PVCs and NSVT in patients with MBs. Exercise significantly increases QTd in MB patients, with an even greater increase in QTd in MB patients with NSVT. Exercise in MB patients results in ventricular arrhythmias and abnormalities in repolarization.

Impact of myocardial bridging on the long-term clinical outcomes of patients with left anterior descending coronary artery disease treated with a drug-eluting stent.

BACKGROUND: Myocardial bridging (MB) is mostly confined to the left anterior descending coronary artery (LAD) and has been reported to be correlated with increased atherosclerotic plaques in the segment proximal to the bridging. This study aimed to assess the impact of MB on the clinical outcomes of patients with DES implantation in the LAD. METHODS: A total of 551 consecutive patients with DES implantation on LAD from January 2008 to December 2009 were included. Patients were divided into an MB group (n=94, 17.1%) and a non-MB group (n=457, 82.9%) based on angiographic findings. They were followed up for three years to evaluate major adverse cardiac events (MACE), which were defined as all-cause death, myocardial infarction (MI), target lesion revascularisation (TLR) or ischaemic driven target vessel revascularisation (Id-TVR). RESULTS: During three years of follow-up, the rate of MACE was significantly higher in the MB group than in the non-MB group (18.1% vs. 9.8%, p=0.024), especially rates of TLR (8.5% vs. 2.4%; p=0.003) and Id-TVR (13.8% vs. 4.2%; p<0.001). However, no difference was observed for MI (3.2 vs. 2.6%; p=0.692) and all-cause death rates (3.2 vs. 4.6%; p=0.575). Multivariate regression analysis showed that the presence of MB was an independent predictor for MACE (Hazard ratio 2.897, 95% CI 1.536 - 5.464, p=0.001). CONCLUSION: MB appears to be associated with adverse effects in patients with DES implantation in the LAD.

Outcome of repair of myocardial bridging at the time of septal myectomy.

BACKGROUND: Myocardial bridging describes systolic compression of the muscular investment of a portion of an epicardial coronary artery. We evaluated the outcome of muscular bridge unroofing of the left anterior descending artery at the time of septal myectomy in patients with hypertrophic cardiomyopathy. METHODS: We conducted a case-controlled study of 36 patients (23 men; median age, 42 years) with hypertrophic cardiomyopathy and myocardial bridging. Group 1 patients had septal myectomy and concomitant unroofing (n = 13), group 2 patients underwent myectomy alone (n = 10), and group 3 patients were treated medically (n = 13). RESULTS: Angina was more prevalent preoperatively in group 1, 46% compared with 20% in group 2. Preoperative left ventricular outflow tract gradients of 67.8 ± 58.2 mm Hg and 74.1 ± 19.7 mm Hg were reduced to 1.9 ± 2.9 mm Hg in group 1 (p < 0.0001) and to 5.6 ± 8.8 mm Hg in group 2 (p < 0.0001). In the surgical groups, there were no early deaths or complications related to unroofing. Survival at 10 years was 83.3% in group 1 (p = 0.297), 100.0% in group 2, and 67.9% in group 3; there were no late sudden deaths. At follow-up, 77% in group 1 were asymptomatic compared with 70% of patients in group 2 (p = 0.19). There was no recurrent angina in group 1. CONCLUSIONS: Myocardial unroofing can be performed safely at the time of septal myectomy for left ventricular outflow tract obstruction. Angina was improved, but we found no difference in late survival compared with patients who had myocardial bridging and myectomy alone. Unroofing should be considered in patients with angina who have significant left anterior descending artery bridging and require myectomy.

Long-term prognosis and outcome in patients with a chest pain syndrome and myocardial bridging: a 64-slice coronary computed tomography angiography study.

BACKGROUND: Small case series have associated coronary myocardial bridging (MB) with adverse cardiac events. However, the clinical significance of MB in unselected patients with chest pain remains unclear. The purpose of this study was to explore the relation between the presence of isolated MB and subsequent adverse cardiac events in symptomatic patients referred for coronary computed tomography angiography (CCTA). METHODS AND RESULTS: Three hundred and thirty-four consecutive patients (age 57 ± 13 years, 43% female) with chest pain and no prior history of coronary artery disease (CAD) who underwent 64-slice CCTA and had no obstructive CAD (≥ 50% coronary luminal obstruction) were included. Patients were followed for cardiac events [cardiovascular (CV) death or non-fatal myocardial infarction (MI)] over 6.1 ± 1 years. Outcomes were compared between patients with MB vs. those without MB using the Cox models. MB was present in 117 out of 334 (35%) patients on CCTA and 80% of MB involved the mid-distal left anterior descending coronary artery. During a mean follow-up duration of 6.1 ± 1 years, cardiac events occurred in 6 out of 117 (5.1%) patients with, and 7 out of 217 (3.2%) patients without MB (P = 0.40). Univariate predictors of cardiac events were hypertension [hazards ratio (HR) = 10.6, P = 0.002], diabetes mellitus (HR = 4.8, P = 0.01), and older age (HR = 1.1, P = 0.0004). The association of hypertension and age with adverse cardiac events remained statistically significant after adjusting for other variables. Neither the presence nor the extent of MB was associated with an increased risk of cardiac events. CONCLUSION: MB is a common finding on CCTA among patients presenting with chest pain but no obstructive CAD. No association was evident between MB and the risk of CV death or MI.

Myocardial bridging on coronary CTA: an innocent bystander or a culprit in myocardial infarction?

Myocardial bridging describes the clinical entity whereby a segment of coronary artery is either partially or completely covered by surrounding myocardium. It represents the most frequent congenital coronary anomaly and has an estimated prevalence of ≤13% on angiographic series. With the emergence of cardiac computed tomography and its ability to simultaneously image the coronary arteries and also the myocardium, there has been an apparent increase in the detection rates of myocardial bridges (prevalence as high as 44%). It has now become important to evaluate their clinical significance. Myocardial bridging is generally considered a benign entity with survival rates of 97% at 5 years; however, there is now emerging evidence that certain myocardial bridge characteristics may be associated with cardiovascular morbidity. The length and depth of myocardial bridges have been associated with increased atherosclerosis, whereas the degree of systolic compression has been associated with ischemia on myocardial perfusion single-photon emission tomography. On the basis of current evidence, it appears that limiting further testing for ischemia to symptomatic patients with long and/or deep myocardial brides would be appropriate.

Morphological changes associated with hemodynamically significant myocardial bridges in sudden cardiac death.

UNLABELLED: Although myocardial bridging (MB) is a common coronary anomaly, its cardiovascular consequences are still disputed. A positive link between sudden cardiac death (SCD) and myocardial bridging has not yet been definitively proved, even though many case reports and small scale studies support this association. For myocardial bridging to be associated with sudden cardiac death it must exhibit certain specific characteristics involving coronary or myocardial changes sufficient to explain a terminal cardiac event. In this study we aimed to analyze the morphological changes (both myocardial and coronary) associated with hemodynamically significant myocardial bridging and the morphological differences between hemodynamically significant MB and MB considered to be non-hemodynamically significant. MATERIAL AND METHOD: We analyzed 53 cases of sudden cardiac death, of which 21 cases had hemodynamically significant myocardial bridging, 14 had non-hemodynamically significant myocardial bridging and 20 cases suffered sudden cardiac death without myocardial bridging, using a morphological score with seven histological parameters. RESULTS: Myocardial fibrosis and interstitial edema were found to be highly correlated with hemodynamically significant myocardial bridging (HSMB), as were interstitial edema and interstitial fibrosis. CONCLUSIONS: Hemodynamically significant myocardial bridging can be discovered during heart dissection by analyzing a series of morphological markers (width, distribution of atherosclerosis, distal hypoplasia). Our study showed that MB was associated with increased myocardial fibrosis and edema, both of which have an increased risk of electrical instability. Compared to non-hemodynamically significant myocardial bridging, HSMB shows a distinct histological pattern, with increased myocardial fibrosis and edema. The main cause of SCD in association with HSMB seems to be electrical due to increased electrical myocardial heterogeneity, but large scale studies are needed to test this.

Incidence, clinical characteristics, and 4-year follow-up of patients with isolated myocardial bridge: a retrospective, single-center, epidemiologic, coronary arteriographic follow-up study in southern Turkey.

INTRODUCTION: Myocardial bridge is a rare coronary anomaly that is generally considered to be benign. The true incidence and long-term prognosis are still under debate. Therefore, we investigated the prevalence and prognosis of patients with isolated myocardial bridge in our center. METHOD: This study is a retrospective, angiographic follow-up which includes 14,250 patients. Median follow-up was 4 years. The typical angiographic finding of myocardial bridging (MB) is systolic narrowing of an epicardial artery. Exclusion criterion was myocardial bridge with coronary artery disease (CAD). The primary end point was major cardiac events (death, myocardial infarction, and revascularization). RESULTS: Myocardial bridge was observed in 118 (0.83%) patients without CAD. The median age was 56.2. There were 30 (25.5%) male and 88 (74.5%) female patients. The arterial segment that was most frequently involved was the left anterior descending artery, as evident in 91 patients (77.2%). Most of the myocardial bridge produces a systolic narrowing between 30% and 50%. There was no major adverse cardiac event nor a need for any revascularization in the follow-up period with medical treatment. CONCLUSION: Isolated myocardial bridge is a benign and rare coronary anomaly. However, further studies are needed to detect long-term prognosis.

Surgical treatment of myocardial bridging: report of 31 cases.

BACKGROUND: Myocardial bridging (MB) is usually considered a benign condition but may result in myocardial ischemia, myocardial infarction (MI), exercise-induced tachycardia, atrioventricular conduction block or even sudden cardiac death. This retrospective study summarizes our operative methods and outcomes for treatment of 31 cases of MB. METHODS: From January 1997 to December 2006, 31 consecutive patients (24 men and 7 women; aged 35 - 67 years; mean 52.3 years) with MB underwent surgical treatment. Thirteen patients had MB only and 18 patients had MB associated with other heart diseases. In preoperative cardiac function grading, 5 patients were in NYHA class I and 18 in NYHA class II and 8 in NYHA class III. Among them, 15 underwent myotomy and 16 underwent coronary artery bypass grafting (CABG). RESULTS: All patients survived and recovered uneventfully. Neither hospital or late death nor major complications occurred. Postoperative exercise testing in all patients failed to reveal any persistent ischemia. Follow-up time was 3 - 115 months (mean 31 months). Follow-up angiographic studies in 21 patients (68%) demonstrated restoration of coronary blood flow and myocardial perfusion without significant residual compression of the artery. All patients were symptom-free and currently in NYHA class I - II. CONCLUSION: The patients who are refractory to medication should actively undergo the surgical procedures such as myotomy and CABG. Myotomy should be advocated as the first choice because of its safety and satisfactory results.