Does optimal delay improve outcomes in the surgical management of post MIVSR?

Post-myocardial infarct ventricular septal rupture (PMIVSR) is a serious mechanical complication which carries a very high mortality if not treated surgically. Since the first closure described by Cooley in 1957, techniques have evolved and results have improved. It is a challenge, not only technically but also in the management, right from admission preoperatively to discharge. Mechanical circulatory support has helped improve outcomes in this sick cohort. In spite of this, 30-day mortality rates in different studies continue to be in the range of 20 to 60% [1–5]. There are not many large series to deeply analyze predictors of outcome, which are multivariate. Cardiogenic shock, posterior infarcts, operating early, and presence of renal dysfunction have been all known to be associated with poorer outcomes.

The authors of the paper on post-myocardial infarct ventricular septal rupture in this issue [6], a series of 71 patients over an 8-year period in a large institution with multiple surgeons, make a pitch for what they term as an “optimal delay” [6]. The 30-day mortality in this study is relatively high compared to few other series [1, 3, 5, 6] in spite of the strategy of optimal delay. The strategy of optimal delay is probably to obtain a window to gain some tissue strength, and stabilize the patient medically with support, to achieve a better outcome. In our experience, we follow a similar strategy since 2008. Mechanical support with intra-aortic balloon pump (IABP) benefits patients up to 48 h, with no added benefit beyond this period, and is crucial for organ systems to stabilize, acidosis to correct, and tissue strength to get better. The very high mortality noted in many papers on patients operated within 48 h [1] is due to the profound myocardial dysfunction and also due to the presence of significant residual shunts, which is directly related to tissue strength. Gaining even 1 day matters. Instituting extra corporeal membrane oxygenation (ECMO) [1, 3] for patients that are much sicker and in shock may be a better option and help push this optimal window a little more to the right favoring better tissue strength. There is no specific direction and patients’ factors have to be taken in to make the decision, as the variables are many.

The reason to judiciously delay is one, to stabilize the system from shock and low output and the second is to have reasonable tissue strength, as residual ventricular septal rupture (VSR) has a very adverse outcome. They have also found that the location of the VSR was not a determinant of poor outcome, which we also observed, but infero-posterior defects have been shown to do badly in other series [1–3]. Most of the patients who get through the 30-day timeline do well and the results of the authors in terms of survival and major adverse cardiac events (MACE) are consistent with most observations including ours [1–6]. Surgical technique has a bearing on the outcome and the authors have adopted the standard Daggett sandwich technique. Residual VSR and bleeding can be very serious in this group of patients and careful attention to technique is important, especially in handling, suturing, and tying of knots. Among survivors, the incidence of residual VSRs is pretty low in this series [4–6], but with a 30-day mortality of more than 50%, it is a possibility that the incidence of residual shunts was higher. The goal is to achieve a shunt-free septum and revascularize as needed [1, 2, 5].

We follow the same strategy of instituting IABP soon after diagnosis and closely monitor them with hourly urine output and twice a day serum creatinine. Any change in the pattern, suggesting a low cardiac output, is the time to intervene. Most of the patients improve over a 24 to 72-h period and decision to intervene is taken on a continuous basis. Waiting for more than 7 days, even if the patient is stable does not add any benefit and only raises the risk of sudden deterioration, which we have seen. The optimal window is 48 h post-IABP and before the end of the week. The strategy of optimal delay is justified.

Long-term survival depends on left ventricular function and freedom from congestive heart failure. Many series have shown that once the 30-day period is over, the survival rates are encouraging. Ventricular arrhythmias [1, 5, 6] are an issue and may be a cause of sudden death. We routinely place all our patients on amiodarone postoperatively for at least 6 months [4]. It may be a good idea in some patients with aneurysmal ventricles to have some low-dose anticoagulation on board.

The scoring system proposed by the authors is the nucleus of the paper [4]. It is based on five preoperative parameters [4, 6]. The myocardial infarction (MI) to VSR time and VSR to surgery time have been known very well as prognostic indicators as they are surrogate markers for the extent of myocardial injury [1–3, 5]. The shorter the time, the poorer the prognosis. The authors recommend three values as a strategy for timing the surgery, with scores less than 25 calling for immediate surgery and scores more than 75 for elective closure, even by device. They also propose a cut-off of 65 as a prognostic marker with a negative predictive value of 86.70% [4, 6].

The scoring system is a good tool to stratify the pre-op variables and give a predicted chance of survival, but one cannot recommend waiting for 4 to 6 weeks based on a score of 75 or more [4, 6]. It will be a very difficult proposition to do a large multicentric study to validate this as suggested by the authors but may be a good idea to use this as a risk stratification tool and not a decision-making one.

Our take on this subject would be somewhat along the lines of the authors, to get the optimal window with IABP support with critical monitoring and close observation and not to wait more than 7 days, even if the patient is extremely stable. We would call it rather as preoperative optimization than delay. This strategy has helped us with good results over a 15-year period of over 44 patients with a 30-day mortality of 20% and a linearized survival of 77.7% at 5 years and 67% at 10 years. The golden window, if one may call, is 2–5 days after institution of the IABP, not exceeding 7 days. With the current usage and comfort of ECMO, extended optimization is possible to achieve better outcomes in future.