Episode 93: CABG with Tom Metkus

In the episode, episode 93, I welcome Dr. Tom Metkus back to the show to discuss perioperative considerations for CABG surgery.

References:

Syntax Trial: https://www.nejm.org/doi/full/10.1056/NEJMoa0804626

STICH Trial: https://www.nejm.org/doi/full/10.1056/NEJMoa1100356

ROOBY Trial: https://www.nejm.org/doi/full/10.1056/NEJMoa0902905

CORONARY Trial: https://www.nejm.org/doi/full/10.1056/NEJMoa1200388

PREVENT IV Trial: https://www.ncbi.nlm.nih.gov/pubmed/16287955

ART Trial: https://www.nejm.org/doi/full/10.1056/NEJMoa1610021

2 Replies to “Episode 93: CABG with Tom Metkus”

  1. Thanks again for a great talk! I have a few comments and questions.

    1. Hemodynamic monitoring with PAC vs ECHO. Thank you for pointing out that it is important to treat the patient rather than treating the ECHO (or the PAC). I think these two monitors give complementary information that can help answer clinical questions. Neither monitor tells a complete story and cannot replace clinical assessments. There are patients in acute respiratory failure requiring mechanical ventilation with clinical signs of congestion and completely normal ECHO (including diastology), who can quickly liberate from the ventilator after aggressive diuresis. There are also patients with baseline well compensated heart failure and severely reduced LVEF in septic shock, who quickly get better by the usual management of sepsis with early antibiotics and fluid resuscitation. Clinical assessments and managing the pathophysiology of the acute illness lead to the rapid improvements in these patients, whereas decisions solely based on ECHO could conceivably lead to different paths.

    2. Calcium channel blocker in the immediate postop period. There is the broad recommendation about avoiding CCB in patients with HFrEF but the details seem to be more complex. I wonder if you can shed some light on this issue specifically pertaining to the immediate postop period for the management of transient hypertension. Dihydropyridine type of CCB such as nicardipine or clevidipine drip is commonly used for treating hypertension in the immediate postop period after cardiac surgery with well documented favorable hemodynamic profile. Similarly, Dr. Metkus mentioned using amlodipine for hypertension. My understanding is that the non-dihydropyridine type of CCBs are contraindicated in HFrEF patients, whereas the dihydropyridine type of CCBs can be used cautiously for hypertension in patients with HFrEF but they potentially limit the optimal titration of HF meds and are not associated with improved outcome. As far as using nicardipine or clevidipine for hypertension in the immediate postop period in patients with reduced LVEF, are you aware of any data or recommendation against this practice?

    3. Myocardial infarction associated with cardiac surgery or type-5 MI. The area I would like further clarification is about the specific EKG changes used in the definition of type-5 MI. It includes new pathological Q wave or new LBBB but not ST segment changes. As Dr. Metkus explained in the talk, ST segment changes are common after cardiac surgery. As a result I can see why ST changes are not included in the definition to increase specificity. The confusion associated with this definition is that it gives the impression that ST changes are not indicative of myocardial ischemia or infarction in the initial 48 hours. If I suspect MI based on clinical ground and the troponin is > 10 * upper limit of normal and the EKG shows ST depression or elevation, then I think I should be very concerned and would proceed with further diagnostic testing such as ECHO and discuss with cardiology and CT surgery about angiogram. On the other hand, if the EKG is repeatedly normal without ST segment or T wave changes despite the clinical concern and high troponin, does it rule out type-5 MI? The definition of type-5 MI is not helpful here because it does not care about ST segments or T waves. Can you please shed some light on this topic? The type-5 MI cases we have seen were associated with new ST changes and clinical deterioration such as worsening heart failure or shock. The diagnoses were based on troponin supported by either echo or angiogram. To complicate things even more, someone in theory could have type-1 or type-2 MI during the initial 48 hours after cardiac surgery based on different mechanisms.

    1. Hi Huayong,

      Great points and great questions, as always.

      In regards to CCB Dr. Metkus and I both agree with the points you make and are not aware of data that would argue against using nicardipine, for example, in post-op cardiac patients. We use it all the time.

      In regards to type-5 MI, I would agree, you have to take the whole picture into account. If you have a normal EKG with major troponin rise it does not rule out type-5 MI and you should likely still work it up. And particularly concerning EKG changes such as ST elevations only the exact territory that was just grafted might make you think twice even if your troponin is not 10x normal.

      So ultimately, as is so often the case, you have to use the guidelines and the evidence in conjunction with your clinical judgment and always involving a team based discussion including the surgeon, the ICU team, cardiology and others.

      Best,
      Jed

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