Nicholas G. Smedira

Durability of mitral valve repair for degenerative disease

BACKGROUND Degenerative mitral valve disease is the most common cause of mitral regurgitation in the United States. Mitral valve repair is applicable in the majority of these patients and has become the procedure of choice. OBJECTIVE This study was undertaken to identify factors influencing the durability of mitral valve repair. PATIENTS AND METHODS Between 1985 and 1997, 1072 patients underwent primary isolated mitral valve repair for valvular regurgitation caused by degenerative disease. Repair durability was assessed by multivariable risk factor analysis of reoperation. It was supplemented by a search for valve-related risk factors for death before reoperation. Three hospital deaths occurred (0.3%); complete follow-up (4152 patient-years) was available in 1062 of 1069 hospital survivors (99.3%). RESULTS At 10 years, freedom from reoperation was 93%. Among 30 patients who required reoperation for late mitral valve dysfunction, the repair failed in 16 (53%) as a result of progressive degenerative disease. Durability of repair was adversely affected by pathologic conditions other than posterior leaflet prolapse, use of chordal shortening, annuloplasty alone, and posterior leaflet resection without annuloplasty. Durability was greatest after quadrangular resection and annuloplasty for posterior leaflet prolapse and was enhanced by the use of intraoperative echocardiography. Death before reoperation was increased in patients having isolated anterior leaflet prolapse or valvular calcification and by use of chordal shortening or annuloplasty alone. CONCLUSIONS Repair durability is greatest in patients with isolated posterior leaflet prolapse who have posterior leaflet resection and annuloplasty. Chordal shortening, annuloplasty alone, and leaflet resection without annuloplasty jeopardize late results.

Unexpected Abrupt Increase in Left Ventricular Assist Device Thrombosis

BACKGROUND We observed an apparent increase in the rate of device thrombosis among patients who received the HeartMate II left ventricular assist device, as compared with preapproval clinical-trial results and initial experience. We investigated the occurrence of pump thrombosis and elevated lactate dehydrogenase (LDH) levels, LDH levels presaging thrombosis (and associated hemolysis), and outcomes of different management strategies in a multi-institutional study. METHODS We obtained data from 837 patients at three institutions, where 895 devices were implanted from 2004 through mid-2013; the mean (±SD) age of the patients was 55±14 years. The primary end point was confirmed pump thrombosis. Secondary end points were confirmed and suspected thrombosis, longitudinal LDH levels, and outcomes after pump thrombosis. RESULTS A total of 72 pump thromboses were confirmed in 66 patients; an additional 36 thromboses in unique devices were suspected. Starting in approximately March 2011, the occurrence of confirmed pump thrombosis at 3 months after implantation increased from 2.2% (95% confidence interval [CI], 1.5 to 3.4) to 8.4% (95% CI, 5.0 to 13.9) by January 1, 2013. Before March 1, 2011, the median time from implantation to thrombosis was 18.6 months (95% CI, 0.5 to 52.7), and from March 2011 onward, it was 2.7 months (95% CI, 0.0 to 18.6). The occurrence of elevated LDH levels within 3 months after implantation mirrored that of thrombosis. Thrombosis was presaged by LDH levels that more than doubled, from 540 IU per liter to 1490 IU per liter, within the weeks before diagnosis. Thrombosis was managed by heart transplantation in 11 patients (1 patient died 31 days after transplantation) and by pump replacement in 21, with mortality equivalent to that among patients without thrombosis; among 40 thromboses in 40 patients who did not undergo transplantation or pump replacement, actuarial mortality was 48.2% (95% CI, 31.6 to 65.2) in the ensuing 6 months after pump thrombosis. CONCLUSIONS The rate of pump thrombosis related to the use of the HeartMate II has been increasing at our centers and is associated with substantial morbidity and mortality.

Color M-mode Doppler flow propagation velocity is a preload insensitive index of left ventricular relaxation: animal and human validation

OBJECTIVES To determine the effect of preload in color M-mode Doppler flow propagation velocity (v(p)). BACKGROUND The interpretation of Doppler filling patterns is limited by confounding effects of left ventricular (LV) relaxation and preload. Color M-mode v(p) has been proposed as a new index of LV relaxation. METHODS We studied four dogs before and during inferior caval (IVC) occlusion at five different inotropic stages and 14 patients before and during partial cardiopulmonary bypass. Left ventricular (LV) end-diastolic volumes (LV-EDV), the time constant of isovolumic relaxation (tau), left atrial (LA) pre-A and LV end-diastolic pressures (LV-EDP) were measured. Peak velocity during early filling (E) and v(p) were extracted by digital analysis of color M-mode Doppler images. RESULTS In both animals and humans, LV-EDV and LV-EDP decreased significantly from baseline to IVC occlusion (both p < 0.001). Peak early filling (E) velocity decreased in animals from 56 +/- 21 to 42 +/- 17 cm/s (p < 0.001) without change in v(p) (from 35 +/- 15 to 35 +/- 16, p = 0.99). Results were similar in humans (from 69 +/- 15 to 53 +/- 22 cm/s, p < 0.001, and 37 +/- 12 to 34 +/- 16, p = 0.30). In both species, there was a strong correlation between LV relaxation (tau) and v(p) (r = 0.78, p < 0.001, r = 0.86, p < 0.001). CONCLUSIONS Our results indicate that color M-mode Doppler v(p) is not affected by preload alterations and confirms that LV relaxation is its main physiologic determinant in both animals during varying lusitropic conditions and in humans with heart disease.

Early results with partial left ventriculectomy

OBJECTIVE We sought to determine the role of partial left ventriculectomy in patients with dilated cardiomyopathy. METHODS Since May 1996 we have performed partial left ventriculectomy in 53 patients, primarily (94%) in heart transplant candidates. The mean age of the patients was 53 years (range 17 to 72 years); 60% were in class IV and 40% in class III. Preoperatively, 51 patients were thought to have idiopathic dilated cardiomyopathy, one familial cardiomyopathy, and one valvular cardiomyopathy. As our experience accrued we increased the extent of left ventriculectomy and more complex mitral valve repairs. For two patients mitral valve replacement was performed. For 51 patients the anterior and posterior mitral valve leaflets were approximated (Alfieri repair); 47 patients also had ring posterior annuloplasty. In 27 patients (51%) one or both papillary muscles were divided, additional left ventricular wall was resected, and the papillary muscle heads were reimplanted. RESULTS Echocardiography showed a significant decrease in left ventricular dimensions after resection (8.3 cm to 5.8 cm), reduction in mitral regurgitation (2.8+ to 0), and increase in forward ejection fraction (15.7% to 32.7%). Cardiac index did not increase significantly (2.2 to 2.4 L/min per square meter). Eight patients (15%) required a perioperative left ventricular assist device; one died and was the only perioperative mortality (1.9%). At 11 months, actuarial survival was 87% and freedom from relisting for transplantation was 72%. CONCLUSIONS Improved selection criteria are necessary to avoid early failures, and much more follow-up and analyses of data are mandatory. However, the operation may become a biologic bridge, or even alternative, to transplantation.

Radial Artery Bypass Grafts Have an Increased Occurrence of Angiographically Severe Stenosis and Occlusion Compared With Left Internal Mammary Arteries and Saphenous Vein Grafts

Background—The radial artery has been increasingly used in CABG. However, angiographic outcome data have been limited. Methods and Results—We reviewed all coronary angiography procedures from February 1996 to October 2001 and selected patients with a radial artery bypass graft. Angiographic outcomes were divided into groups as (1) occluded, (2) severe disease (≥70% stenosis, or string sign), or (3) patent (<70% stenosis). Multivariable analyses determined predictors of severe disease or occlusion. A total of 310 patients had a radial artery graft. Mean follow-up after coronary artery bypass grafting was 565 ± 511 days. Radial artery grafts had a patency rate of 51.3%, which was significantly lower than that for left internal mammary arteries (90.3%, P < 0.0001) or saphenous vein grafts (64.0%, P = 0.0016). Radial artery grafts had an occlusion rate of 33.7%, compared with 4.8% for left internal mammary arteries (P < 0.0001), and had a severe stenosis rate of 15.1%, compared with 5.9% for saphenous vein grafts (P = 0.0003) and 4.8% for left internal mammary arteries (P < 0.0001). Women had a worse overall radial artery patency rate than men (38.9% versus 56.1%, P = 0.025). A radial artery graft was the most powerful multivariable predictor of severe stenosis or occlusion (χ2 = 28.87, P < 0.0001). Because of diseased radial artery grafts, 58 patients required subsequent percutaneous intervention, and 26 patients required repeat CABG. Conclusions—In patients predominantly presenting with signs and symptoms of myocardial ischemia after CABG, radial artery grafts have lower patency rates than left internal mammary artery and saphenous vein grafts. Selective use of the radial artery is warranted, particularly in women.

Preoperative Risk Factors for Right Ventricular Failure After Implantable Left Ventricular Assist Device Insertion

BACKGROUND Implantable left ventricular assist device (LVAD) insertion complicated by early right ventricular (RV) failure has a poor prognosis and is generally unpredictable. METHODS To determine preoperative risk factors for perioperative RV failure after LVAD insertion, patient characteristics and preoperative hemodynamics were analyzed in 100 patients with the HeartMate LVAD (Thermo Cardiosystems, Inc, Woburn, MA) at the Cleveland Clinic. RESULTS RV assist device support was required for 11 patients (RVAD group). RVAD use was significantly higher in younger patients, female patients, smaller patients, and myocarditis patients. There was no significant difference in the cardiac index, RV ejection fraction, or right atrial pressure between the two groups preoperatively. The preoperative mean pulmonary arterial pressure (PAP) and RV stroke work index (RV SWI) were significantly lower in the RVAD group (p = 0.015 and p = 0.011, respectively). Survival to transplant was poor in the RVAD group (27%) and was 83% in the no-RVAD group. CONCLUSIONS The need for perioperative RVAD support was low, only 11%. Preoperative low PAP and low RV SWI were significant risk factors for RVAD use.

Outcome of patients with hypertrophic obstructive cardiomyopathy after percutaneous transluminal septal myocardial ablation and septal myectomy surgery.

OBJECTIVES This study was conducted to evaluate follow-up results in patients with hypertrophic obstructive cardiomyopathy (HOCM) who underwent either percutaneous transluminal septal myocardial ablation (PTSMA) or septal myectomy. BACKGROUND Controversy exists with regard to these two forms of treatment for patients with HOCM. METHODS Of 51 patients with HOCM treated, 25 were treated by PTSMA and 26 patients via myectomy. Two-dimensional echocardiograms were performed before both procedures, immediately afterwards and at a three-month follow-up. The New York Heart Association (NYHA) functional class was obtained before the procedures and at follow-up. RESULTS Interventricular septal thickness was significantly reduced at follow-up in both groups (2.3 +/- 0.4 cm vs. 1.9 +/- 0.4 cm for septal ablation and 2.4 +/- 0.6 cm vs. 1.7 +/- 0.2 cm for myectomy, both p < 0.001). Estimated by continuous-wave Doppler, the resting pressure gradient (PG) across the left ventricular outflow tract (LVOT) significantly decreased immediately after the procedures in both groups (64 +/- 39 mm Hg vs. 28 +/- 29 mm Hg for PTSMA, 62 +/- 43 mm Hg vs. 7 +/- 7 mm Hg for myectomy, both p < 0.0001). At three-month follow-up, the resting PG remained lower in the PTSMA and myectomy groups (24 +/- 19 mm Hg and 11 +/- 6 mm Hg, respectively, vs. those before procedures, both p < 0.0001). The NYHA functional class was also significantly improved in both groups (3.5 +/- 0.5 vs. 1.9 +/- 0.7 for PTSMA, 3.3 +/- 0.5 vs. 1.5 +/- 0.7 for myectomy, both p < 0.0001). CONCLUSIONS Both myectomy and PTSMA reduce LVOT obstruction and significantly improve NYHA functional class in patients with HOCM. However, there are benefits and drawbacks for each therapeutic method that must be counterbalanced when deciding on treatment for LVOT obstruction.

Mitral valve surgery in patients with severe left ventricular dysfunction

OBJECTIVES The objectives of this study were to determine (1) survival, (2) functional status and freedom from readmission for heart failure and (3) change in postoperative left ventricular (LV) dimensions and function following mitral valve repair or replacement in patients with severe LV dysfunction and mitral regurgitation. PATIENTS AND METHODS Between 1990 and 1998, 44 patients with mitral regurgitation and a LV ejection fraction <35% (mean+/-SD, 28+/-6%) underwent isolated mitral repair (n=35) or replacement (n=9). The etiology of regurgitation was valvular in 18 (40%) patients, ischemic in 13 (30%) patients and dilated idiopathic cardiomyopathy in 13 (30%) patients. Every patient had been hospitalized one to six times for symptoms of heart failure (mean+/-SD, 2.3+/-1.5). All patients were receiving maximal drug therapy with 15 (34%) in New York Heart Association (NYHA) class III and 12 (27%) in class IV. Seven (16%) patients were initially referred for consideration of transplantation. The mean+/-SD duration of follow-up was 40+/-21 months. RESULTS One (2.3%) patient died 9 days postoperatively of acute bronchopneumonia. The mean+/-SD duration of ICU and hospital stay was 41+/-34 h and 9+/-3 days, respectively. The 1-, 2- and 5-year survival rates were 89, 86 and 67%, respectively. Heart failure and sudden death accounted for 62% of the late deaths. The NYHA class improved for survivors from 2.8+/-0.8 preoperatively to 1. 2+/-0.5 at follow-up (P<0.0001). Freedom from readmission for heart failure was 88, 82 and 72% at 1, 2 and 5 years, respectively. No patient has been listed for transplantation. CONCLUSIONS Mitral valve surgery offers symptomatic improvement and survival benefit in patients with severe LV dysfunction and mitral regurgitation. More liberal use of this surgery for cardiomyopathy patients is warranted.

Cardiac magnetic resonance detection of myocardial scarring in hypertrophic cardiomyopathy: correlation with histopathology and prevalence of ventricular tachycardia.

OBJECTIVES In hypertrophic cardiomyopathy (HCM) patients undergoing surgical myectomy, we sought to determine the association between pre-operative cardiac magnetic resonance (CMR) findings, small intramural coronary arteriole dysplasia (SICAD) on histopathology, and ventricular tachycardia (VT). BACKGROUND Myocardial scarring (fibrosis) and SICAD are frequently observed on histopathology in HCM patients. CMR measures wall thickness and detects scar. METHODS Sixty symptomatic HCM patients (62% men; mean age 51 +/- 14 years), with preserved ejection fraction (mean 64 +/- 5%) and no angiographic coronary disease underwent CMR (cine and delayed post-contrast) using a Siemens 1.5 T scanner, followed by septal myectomy. Maximal basal septal thickness was recorded on cine CMR. Scar was determined (percentage of total myocardium) on delayed post-contrast CMR images and quantified as none, mild (0% to 25%), moderate (26% to 50%), or severe (>50%). VT was assessed using Holter monitoring. Degree of SICAD was determined (normal, mild, moderate, and severe) on histopathology of surgical specimen. RESULTS SICAD and scar were seen in 45 (75%) and 38 (63%) patients, respectively. In 15 patients without SICAD, 12 (80%) had no scar; 23 (70%) patients with mild SICAD had mild scar on CMR. On multivariate analysis, degree of SICAD was independently associated with scar on CMR (Wald chi-square statistic: 6.8, p < 0.01). Patients with basal septal scar on CMR had higher VT frequency compared with those without (27% vs. 5%, p = 0.03). CONCLUSIONS A strong association exists between degree of SICAD and myocardial scarring seen on CMR.

Updated Meta-Analysis of Septal Alcohol Ablation Versus Myectomy for Hypertrophic Cardiomyopathy

OBJECTIVES The purpose of this study was to perform a systematic review and meta-analysis of comparative studies to compare outcomes of septal ablation (SA) with septal myectomy (SM) for treatment of hypertrophic obstructive cardiomyopathy (HOCM). BACKGROUND SM is considered the gold standard for treatment of HOCM. However, SA has emerged as an attractive therapeutic alternative. METHODS A Medline search using standard terms was conducted to determine eligible studies. Due to a lack of randomized control trials, we included observational studies for review. RESULTS Twelve studies were found eligible for review. No significant differences between short-term (risk difference [RD]: 0.01; 95% confidence interval [CI]: -0.01 to 0.03) and long-term mortality (RD: 0.02; 95% CI: -0.05 to 0.09) were found between the SA and SM groups. In addition, no significant differences could be found in terms of post-intervention functional status as well as improvement in New York Heart Association functional class, ventricular arrhythmia occurrence, re-interventions performed, and post-procedure mitral regurgitation. However, SA was found to increase the risk of right bundle branch block (RBBB) (pooled odds ratio [OR]: 56.3; 95% CI: 11.6 to 273.9) along with need for permanent pacemaker implantation post-procedure (pooled OR: 2.6; 95% CI: 1.7 to 3.9). Although the efficacy of both SA and SM in left ventricular outflow tract gradient (LVOTG) reduction seems comparable, there is a small yet significantly higher residual LVOTG amongst the SA group patients as compared with the SM group patients. CONCLUSION SA does seem to show promise in treatment of HOCM owing to similar mortality rates as well as functional status compared with SM; however, the caveat is increased conduction abnormalities and a higher post-intervention LVOTG. The choice of treatment strategy should be made after a thorough discussion of the procedures with the individual patient.