Michael J. Mack M.D.

Arsalan, M., J. J. Squiers, M. A. Herbert, J. C. MacHannaford, T. Chamogeorgakis, S. L. Prince, B. L. Hamman, C. Knoff, D. O. Moore, K. B. Harrington, J. M. DiMaio, M. J. Mack and W. T. Brinkman (2017). “Comparison of outcomes of operative therapy for acute type a aortic dissections provided at high-volume versus low-volume medical centers in north texas.” Am J Cardiol 119(2): 323-327.

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Immediate surgery is standard therapy for acute type A aortic dissections (TAAD). Because of its low incidence, many smaller cardiac surgery programs do not routinely perform this procedure because it may negatively affect outcomes. Many high-risk, low-volume (LV) surgical procedures are now preferentially performed in reference centers. We compared the outcomes of surgery for TAAD in high-volume (HV) and LV centers in a single metropolitan area to determine the optimal setting for treatment. Thirty-five of the 37 cardiac surgery programs in the Dallas Ft. Worth metropolitan area participate in a regional consortium to measure outcomes collected in the Society of Thoracic Surgeons Adult Cardiac Database. From January 01, 2008, to December 31, 2014, 29 programs had treated TAAD. Those programs performing at least 100 operations for TAAD were considered HV centers and the others LV. Surgery for TAAD was performed in 672 patients over the 7-year study period with HV centers performing 469 of 672 (70%) of the operations. Despite similar preoperative characteristics, operative mortality was significantly lower in HV versus LV centers (14.1% vs 24.1%; p = 0.001). There was no significant difference in postoperative paralysis rates (2.6% vs 4.5%; p = 0.196), stroke rates (10.7% vs 9.4%; p = 0.623), or 30-day readmission rates (12.1% vs 15.5%; p = 0.292). An improved survival rate in HV centers was maintained over a 5-year follow-up period. Surgery for TAAD in a single large metropolitan area was most commonly performed in HV centers. In conclusion, the treatment of acute thoracic aortic dissection is recommended to be performed in reference centers because of lower early and midterm mortality.

Mack, M. and D. R. Holmes (2016). “Randomised trials in left main disease: a NOBLE effort.” Lancet 388(10061): 2715-2716.

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The NOBLE trial enrolled 1201 patients in 36 centres, randomly assigned to either PCI primarily with the Biolimus–eluting stent (Biomatrix Flex) or CABG. The primary endpoint was major adverse cardiac and cerebrovascular events including all-cause mortality, myocardial infarction, stroke, and repeat revascularisation at a median follow-up of 3 years. The trial was designed as a non-inferiority trial with a relatively wide confidence interval of 1·35. The primary endpoint occurred in 29% of patients in the PCI group and 19% of patients in the CABG group (HR 1·48 [95% CI 1·11–1·96]), exceeding the limit for non-inferiority and was in fact statistically significant for superiority of CABG over PCI (p=0·0079). Outcomes were similar in both intention-to-treat and per-protocol analyses. Regarding the individual components of the composite primary endpoint, 5 year Kaplan Meier estimates of all-cause mortality and stroke were the same but there were significantly fewer clinically apparent myocardial infarctions and fewer repeat revascularisation procedures with CABG. The conclusion of the trial is that CABG might be superior to PCI for treatment of left main stem coronary artery disease. There are a few specific findings of this trial that are noteworthy and somewhat surprising but there are also some concerns. The first is that the benefit of CABG was noted in all ranges of the SYNTAX score, which is contrary to the SYNTAX trial in which patients with less complex disease did as well with PCI as with CABG. This finding might partly be explained by the fact that 81% of the patients in NOBLE had bifurcation left main disease, which is more difficult to treat than ostial or trunk left main disease and might be associated with a worse outcome with PCI. The second finding is that there was a trend toward a higher incidence of stroke at 5 years with PCI, which is the opposite to what has been noted in most previous comparative trials. This result is perplexing in that with PCI at 30 days, there were no strokes. The stroke rate only gradually increased over time with PCI to an estimated 4·9% at 5 years. The reasons for the late stroke rate in PCI might be due to chance in the absence of any reasons for this late event. The third point is that the trial primary endpoint was changed from the original design. This trial was event driven, in which a specific number of events was needed; this requirement was based on events in the SYNTAX trial. When that number could not be reached in 5 years of follow-up, the primary endpoint was assessed at a median of 3 years. Might that have affected the results? Fourth, procedural purists on both sides will argue that optimal procedures were not done, with only 75% of the patients with PCI undergoing intravascular ultrasound assessment, only 93% of patients with CABG receiving a left internal mammary artery graft, and 86% of patients receiving at least one saphenous vein graft. However, we suspect that this is probably representative of real world practice. (Excerpt from text of this commentary, p. 2715-2716.)

Parasca, C. A., S. J. Head, M. Milojevic, M. J. Mack, P. W. Serruys, M. C. Morice, F. W. Mohr, T. E. Feldman, A. Colombo, K. D. Dawkins, D. R. Holmes, Jr. and P. A. Kappetein (2016). “Incidence, characteristics, predictors, and outcomes of repeat revascularization after percutaneous coronary intervention and coronary artery bypass grafting: The syntax trial at 5 years.” JACC Cardiovasc Interv 9(24): 2493-2507.

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OBJECTIVES: The study sought to determine the incidence, predictors, characteristics, and outcomes of repeat revascularization during 5-year follow-up of the SYNTAX (Synergy Between Percutaneous Coronary Intervention With TAXUS and Cardiac Surgery) trial. BACKGROUND: Limited in-depth long-term data on repeat revascularization are available from randomized trials comparing percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG). METHODS: Incidence and timing of repeat revascularization and its relation to the long-term composite safety endpoint of death, stroke, and myocardial infarction were analyzed in the SYNTAX trial (n = 1,800) using Kaplan-Meier analysis. RESULTS: At 5 years, repeat revascularization occurred more often after initial PCI than after initial CABG (25.9% vs. 13.7%, respectively; p < 0.001), and more often consisted of multiple repeat revascularizations (9.0% vs. 2.8%, respectively; p = 0.022). Significantly more repeat PCI procedures were performed on de novo lesions in patients after initial PCI than initial CABG (33.3% vs. 13.4%, respectively; p < 0.001). At 5-year follow-up, patients who underwent repeat revascularization versus patients not undergoing repeat revascularization had significantly higher rates of the composite safety endpoint of death, stroke, and myocardial infarction after initial PCI (33.8% vs. 16.6%, respectively; p < 0.001), and a trend was found after initial CABG (22.4% vs. 15.8%, respectively; p = 0.07). After multivariate adjustment, repeat revascularization was an independent predictor of the composite safety endpoint after both initial PCI (hazard ratio [HR]: 2.2; 95% confidence interval [CI]: 1.6 to 3.0; p < 0.001) and initial CABG (HR: 1.8; 95% CI: 1.2 to 2.9; p = 0.011). CONCLUSIONS: Repeat revascularization rates are significantly higher after initial PCI than after initial CABG for complex coronary disease. Repeat revascularization is an independent predictor of death, stroke, and myocardial infarction for myocardial revascularization.

Abramowitz, Y., Y. Kazuno, T. Chakravarty, H. Kawamori, Y. Maeno, D. Anderson, Z. Allison, G. Mangat, W. Cheng, A. Gopal, H. Jilaihawi, M. J. Mack and R. R. Makkar (2016). “Concomitant mitral annular calcification and severe aortic stenosis: Prevalence, characteristics and outcome following transcatheter aortic valve replacement.” Eur Heart J: 2016 Dec [Epub ahead of print].

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AIMS: Calcified aortic stenosis (AS) and mitral annular calcification (MAC) have certain similar etiology and pathophysiological mechanisms. MAC is frequently encountered in pre-procedural computed tomography (CT) imaging of patients that undergo transcatheter aortic valve replacement (TAVR), but its prognostic implications for these patients have not been thoroughly investigated. This study sought to evaluate the prevalence of MAC among patients with severe AS and to assess the clinical implications of MAC on these patients during and following TAVR. METHODS AND RESULTS: Consecutive patients that underwent TAVR were compared according to the existence of MAC and its severity in pre-TAVR CT scans. From the entire cohort of 761 patients, 49.3% had MAC, and 50.7% did not have MAC. Mild MAC was present in 231 patients (30.4%), moderate MAC in 72 patients (9.5%), and severe MAC in 72 patients (9.5%). Thirty-day mortality and major complications were similar between patients with and without MAC. In a multivariable survival analysis, severe MAC was found to be an independent strong predictor of overall mortality following TAVR (all-cause mortality: hazards ratio [HR] 1.95, 95% confidence interval [CI] 1.24-3.07, P = 0.004; cardiovascular mortality: HR 2.35, 95% CI 1.19-4.66; P = 0.01). Severe MAC was also found to be an independent strong predictor of new permanent pacemaker implantation (PPI) after TAVR (OR 2.83, 95% CI 1.08-7.47; P = 0.03). CONCLUSION: Half of the patients with severe AS evaluated for TAVR were found to have MAC. Severe MAC is associated with increased all-cause and cardiovascular mortality and with conduction abnormalities following TAVR and should be included in future risk stratification models for TAVR.

Daubert, M. A., N. J. Weissman, R. T. Hahn, P. Pibarot, R. Parvataneni, M. J. Mack, L. G. Svensson, D. Gopal, S. Kapadia, R. J. Siegel, S. K. Kodali, W. Y. Szeto, R. Makkar, M. B. Leon and P. S. Douglas (2016). “Long-term valve performance of tavr and savr: A report from the partner i trial.” JACC Cardiovasc Imaging: 2016 Dec [Epub ahead of print].

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OBJECTIVES: The aim of this study was to evaluate the long-term performance of transcatheter aortic valve replacement (TAVR) and surgical aortic valve replacement (SAVR) through longitudinal echocardiographic analysis. BACKGROUND: The long-term performance of the SAPIEN TAVR is not well-described. Therefore, we examined the hemodynamic and valvular profile of the SAPIEN TAVR over 5 years. METHODS: All patients receiving TAVR or SAVR with first post-implant (FPI) and 5-year echoes were analyzed for aortic valve (AV) peak velocity, AV mean gradient, AV area, peak left ventricular (LV) outflow tract and in-stent velocities, Doppler velocity index, aortic regurgitation (AR), LV mass index, stroke volume index, and cardiac index. The FPI and 5-year data were compared using a paired t test or McNemar’s analyses. RESULTS: There were 86 TAVR and 48 SAVR patients with paired FPI and 5-year echocardiograms. Baseline characteristics were similar between groups. The AV area did not change significantly 5 years after TAVR (p = 0.35). The AV mean gradient also remained stable: 11.5 +/- 5.4 mm Hg at FPI to 11.0 +/- 6.3 mm Hg at 5 years (p = 0.41). In contrast, the peak AV and LV outflow tract velocities decreased (p = 0.03 and p = 0.008, respectively), as did in-stent velocity (p = 0.015). Correspondingly, the TAVR Doppler velocity index was unchanged (p = 0.07). Among TAVR patients, there was no change in total AR (p = 0.40), transvalvular AR (p = 0.37), or paravalvular AR (p = 0.26). Stroke volume index and cardiac index remained stable (p = 0.16 and p = 0.25, respectively). However, there was a significant regression of LV mass index (p < 0.0001). The longitudinal evaluation among SAVR patients revealed similar trends. There was a low rate of adverse events among TAVR and SAVR patients alive at 5 years. CONCLUSIONS: Longitudinal assessment of the PARTNER I trial (THE PARTNER TRIAL: Placement of AoRTic TraNscathetER Valve Trial) demonstrates that valve performance and cardiac hemodynamics are stable after implantation in both SAPIEN TAVR and SAVR in patients alive at 5 years.