Interventional Cardiology: The Numbers Game

A career in the field of interventional cardiology is a road riddled with land mines. A life of caring for the sickest of the sick through providing urgent and immediate lifesaving intervention. Skills that come at a high price and could, at any moment, be taken away by a bad outcome, a lawsuit, or an adverse peer review.

The interventionalist has to provide the crucial care, in the timeframe dictated by the situation, and provide it correctly, yet with an unpredictable end result.

The field of intervention in cardiology started in 1977 when percutaneous transluminal coronary angioplasty (PTCA) was introduced to the United States hospitals by Andreas Gruentzig. PTCA soon spread like wildfire in large hospitals with open heart surgery programs.

In its early days, PTCA had a high rate of acute closure and late complications from wire perforation due to unforgiving poorly steerable wires, stiff guiding catheters, and bulky balloon catheters that often disrupted an already diseased vessel wall, making it prone to dissection and to acute thrombosis. Furthermore, in the eighties and early nineties, platelet inhibition consisted of aspirin alone, which was very inadequate. Angioplasty alone (before the era of stenting) carried a 6-10% risk of acute complications resulting in acute vessel closure immediately or hours after the procedure. Stenting became widely available in 1996 and markedly reduced acute complications.

PTCA also carried a 30% late complication due to restenosis, now addressed by drug-eluting stents that can suppress smooth muscle proliferation. In-stent restenosis is less than 10% (close to 6% in 2019).

The adoption of drug-eluting stenting following gentle PTCA (pre-dilation with PTCA), the routine use of dual antiplatelet inhibition, the introduction of IIB/IIIA inhibitors, and availability of direct thrombin inhibitors (bivalrudin) further enhanced the safety of the procedure, and improved the acute and chronic success rate.

In 1993, the American College of Cardiology (ACC) concluded, based on expert consensus, that high-volume interventionalists with annual volumes of 75 procedure or more have better outcomes than the low-volume operators. It became the standard used by hospitals and credentialing bodies as a criterion to grant or deny interventional privileges.

Over three decades, the annual number of interventions has been used as a marker of competency and became a tool to eliminate competitors in local cardiology communities. The most common scenario is the new interventional cardiologist starting a career at a hospital with an existing cardiology intervention program. The newcomer is building his/ her volume on ST-elevation myocardial infarction (STEMI) cases and non-STEMI/unstable angina cases, whereas the established interventionalist has a steady referral of positive stress test patients and stable angina cases. We now know that the outcomes of STEMI interventions are worse than non-STEMI outcomes, and the non-STEMI outcomes are worse than the more stable cases of angina and abnormal stress test interventions. On the other hand, as the older interventional cardiologist is trying to do fewer procedures and reduce his/her daily workload, he/she is faced with a declining annual intervention volume and hence, becomes at risk of falling below the threshold number.

The new interventionalist in a hospital is at a disadvantage because the case mix is heavily shifted towards the STEMI and non-STEMI cases, and the established interventionalist has a case mix favoring the stable, lower risk population. It goes without saying that the new interventionalist is going to have a worse outcome with a higher complication rate than the established colleague. In addition, when it comes to reviewing the outcomes of the new interventionalist, the review is done by an established interventionalist who is already in the leadership position, possibly as a member of a peer review process, or as the director of cath lab, chair of cardiology, member of the executive committee, or hospital board.

In reviewing the complication rate of the new interventional colleague, the established interventionalist is the judge and the jury, and can potentially use the outcome data or procedure volume numbers to eliminate a competitor and by default, capture extra volume of interventions. For decades, the annual procedure volume and outcomes data have been used as a hatchet to weed out competition in interventional cardiology.

Cardiology intervention in 2019 is a far cry from 1993. The observation about linking competency and annual volume of intervention which, in 1993, held true, does not hold true in 2019. The safety of the procedure has improved tremendously and any attempt to show the effect of operator volume on outcome will require a large-scale study, because in today’s world, both high and low volume operators have a very low complication rate. Today’s complication rates are highly influenced by case mix and the percentage of high risk cases an operator does, i.e., STEMIs, non-STEMIs, etc., rather than a simple total number of cases. It is also influenced by the operator’s years of experience.

In my own thirty-year career as an interventional cardiologist, I was under review whenever a mortality or morbidity case took place. The colleague reviewer was always reasonable and agreed with the intervention approach, but I do recall two unreasonable review situations, both early in my career. One was when I had my first acute PTCA occlusion in a new job. My senior partner met with me to review the case and gave me his valued conclusion, that the vendor of the balloon I used was the reason for the acute occlusion, and he recommended that I use the vendor of the PTCA balloon that he used (there were no issues with either balloons and both are still on the market). The second incident was when I had a stent become partially dislodged from the mounting balloon and I decided to deploy the stent in the right coronary artery (RCA) proximal to the lesion site, because the stent was going to embolize down the RCA. The distal RCA lesion itself was treated with PTCA only, with good results. The cath lab director, an unfriendly competitor, decided to send the case for review by an outside expert reviewer. The case was sent to a friend of his, who reviewed the case and generated a lengthy report discussing the intricacy of the case. The last paragraph said, “In conclusion, the operator did not meet the standard of care because he used a 6 French (Fr) guiding catheter and not a 7 Fr guiding catheter.” This was a convincing argument to the administrator of the hospital, the chair of the peer review committee (who was a gynecologist), and the chief of staff (who was an orthopedic surgeon). At that point, it took three expert opinions from three reputable institutions to convince the hospital administrator, chair of peer review, and chief of staff to reverse the damage and prove that the original outside reviewer was biased and his report inaccurate.

It is time for the ACC to abandon procedure volume as a marker for competency and to recognize that the skill of intervention is maintained over the years even if the numbers fall below an imaginary threshold. The skill of cardiac intervention matures with time and experience, and becomes less dependent on numbers or volume. The risk adjustment and case mix deserves more attention than the mere annual volume. The annual procedure number recommendation has become a political tool by which hospitals and interventionalists compete against each other in the business world, with little or no regard to years of experience or risk-adjusted data outcomes.

In 2013, the ACC modified its position and lowered the recommended percutaneous coronary intervention volume to 50 annually.

The ACC has an obligation to protect its members from being harassed or extorted for having a low annual volume when competency is supported by years of experience. The ACC should also protect new members entering the field from being trapped into doing the high risk cases and being left in the wind for having poor outcomes. 

Jay Bitar, MD, FACC, has been an interventional cardiologist since 1989. He can be contacted at jbbitar@gmail.com.