Recently, the MATRIX trial results were published. The authors randomized > 8000 patients presenting with acute coronary syndromes (ACS) to either transfemoral or transradial approach. Although touted as an overwhelming “win” for the radial approach, to the point of practice and guideline modification in North America, the trial missed the pre-specified α level of significance of 0.025 for the co-primary major adverse cardiovascular events (MACE) endpoint of the composite of all-cause mortality, myocardial infarction (MI), or stroke while meeting a second co-primary net adverse cardiovascular events (NACE) endpoint of the composite of all-cause mortality, MI, stroke, or Bleeding Academic Research Consortium (BARC) 3 or 5 bleed. The individual composites of MACE were not different, with the exception of all-cause mortality, which made statistical significance at a p value of 0.045. Consider the fact that in MATRIX , BARC bleeding (included in NACE endpoint) was driven by a reduction in the composite of type 3 bleeds, the majority being type 3a (overt bleeding plus hemoglobin drop of < 5 g/dL or any transfusion with overt bleeding). Nonetheless, the proportion of BARC type 5 (fatal bleeding) was nearly identical (0.2% vs. 0.3%) between groups and without the statistical differences seen in either major or minor Thrombolysis in Myocardial Infarction (TIMI) bleeds or Global Use of Strategies to Open Occluded Arteries (GUSTO) moderate or severe bleed.

It is possibly a stretch to suggest that radial access reduced bleeding to a degree that affected mortality at 30-days, perhaps further analysis and trials will shed light on this matter. Without a doubt, this trial has reignited the debate in regard to the preferred access for patients presenting with ACS and has received substantial attention in the press suggesting that radial should be the default approach for every patient presenting with ACS. However, we believe that these results should be interpreted with caution and applied in the right clinical context and that one size may not fit all.

The authors suggest that this trial included high-risk individuals based on the number of patients presenting with ST-elevation myocardial infarction (STEMI), the proportion of patients with Killip class > I and positive biomarkers. Nevertheless, the data provided may be interpreted in a different way suggesting that these patients, in fact, may not entirely fit in the high-risk category. The authors acknowledge that 90% of the patients presented with Killip class I. Consistent with this finding, the overall all-cause mortality at 30-days was 1.6% in the radial group and 2.2% in the femoral group. In a prior report , patients presenting with Killip class I had a 30-day mortality under 3%. Killip class II was associated with a more than 3-fold increase in 30-day mortality compared with Killip class I (8.8% vs 2.8%; p < 0.001). Killip class III/IV was associated with a more than 5-fold increase in 30-day mortality compared with Killip class I (14.4% vs 2.8%; p < 0.001). In a multivariable analysis, Killip class III/IV was the most powerful predictor of mortality at both 30 days (hazard ratio [HR], 2.35; 95% confidence interval [CI], 1.69–3.26; p < 001) and 6 months (HR, 2.12; 95% CI, 1.63–2.75; p < 0.001) and was superior to age, ST depression, elevated biomarkers, heart rate, systolic blood pressure, and common aspects of medical history.

Therefore, one can argue that only 10% of the patients included in MATRIX were at a substantial increased risk of death at 30 days. It would be interesting to know if there was a systematic objective risk stratification of patients enrolled in the trial. One can speculate that in the overall population, with a mean age of 65, mean blood pressure of 138, mean heart rate of 76, and most patients having normal kidney function, most patients would not be in the high-risk category either despite positive biomarkers and ST deviations in the presenting electrocardiogram.

The authors also suggest that in MATRIX about 50% of patients had at least 1 complex lesion. However, despite including > 90% of patients with either STEMI or troponin positive non-ST segment elevation ACS only 25% of patients were older than 75 years of age, less than 3.5% of patients (2.6% in the radial group and 3.5% in the femoral group) had previous coronary bypass graft, and patients with a history of renal failure comprised less than 1.5% of the patients. Then, were there any differences in MACE or NACE in this subgroup of patients with complex lesions?

The MATRIX investigators do not report procedural differences in fluoroscopy time and contrast volume, which are important variables operators should consider while performing safe percutaneous intervention (PCI). In RIVAL , the radial group had a small increase in fluoroscopy time of about 1.3 minutes (p < 0.0001). This minor increase in fluoroscopy time may result in a marked increase in radiation exposure to an operator. For instance, if a given operator over the course of few years performs 1000 PCIs, this may result in an increase of 1300 minutes of radiation exposure; therefore, the success of PCI is not related to only procedural outcomes but to safety to the operator and the patient.

Similar to RIVAL the efficacy endpoint in MATRIX showed a benefit in centers with high proportion (80–98%) of radial PCIs (HR 0.64, CI 0.51–0.81, p < 0.001). Furthermore, outcomes at high-volume centers were superior, and overall major bleeding event rates were low, suggesting both access choices can be safely performed when in the hands of a confident and experienced operator.

Although we celebrate the success of radial and femoral access achieving overall low event rates in patients with ACS, we believe that physician’s judgment and comfort with either access is likely to lead to the best possible outcome. Therefore, a contemporary operator should be well versed in both approaches, and final access decisions should be individualized on a patient-by-patient basis because one size does not fit all.