We thank Cantinotti et al for their thoughtful letter regarding our work on the echocardiographic diagnosis of anomalous left coronary artery from the pulmonary artery (ALCAPA) in children. We believe that their letter emphasizes a fundamental point from our work that we are pleased to readdress and highlight.

As the authors have pointed out, the current literature recognizes the challenge of precisely defining coronary artery origins using only transthoracic echocardiography in every patient with ALCAPA. We certainly agree that if the only criterion used in the echocardiographic diagnosis of ALCAPA is clear two-dimensional identification of the anomalous coronary origin, patients will remain at risk for missed diagnosis. However, our data emphasize the additional echocardiographic markers present within these studies, which highlight hemodynamic and ischemic changes key to the understanding of the unique pathophysiology of ALCAPA and valuable in making a timely diagnosis.

The additional markers of ALCAPA described in our report include the following :

• 1.
  

  retrograde flow by color Doppler in the left coronary artery toward the pulmonary artery and away from the aortic root (found in 91% of cases);

  
  
• 2.
  

  linear color Doppler flow signals within the myocardium, indicating collateral coronary vessels (in 85% of cases);

  
  
• 3.
  

  right coronary artery dilatation from excessive collateral flow (in 81% of cases);

  
  
• 4.
  

  abnormal color Doppler signals in the pulmonary artery where the anomalous coronary empties into the pulmonary artery (in 79% of cases);

  
  
• 5.
  

  pathologic mitral regurgitation from watershed papillary muscle ischemia (in 74% of cases);

  
  
• 6.
  

  left ventricular systolic dysfunction (in 66% of cases); and

  
  
• 7.
  

  endocardial fibroelastosis from chronic subendocardial ischemia (in 57% of cases).

These markers, in concert with the ability of echocardiography to identify the anomalous coronary origin from the pulmonary artery directly (in 74% of cases), will confirm diagnosis in virtually every case of ALCAPA if applied correctly. If the coronary artery origins are not clearly shown, the additional markers provide further data that should raise the level of concern for ALCAPA and suggest a more concerted effort to identifying the coronary origins. As Cantinotti et al accurately pointed out from our work, transthoracic echocardiography has been the primary diagnostic tool used in our laboratories in the diagnosis of ALCAPA since 2005, reflecting a commitment to the full description of abnormalities found within ALCAPA. We encourage other laboratories to apply these criteria in the diagnosis of ALCAPA as well.

Although dated, the gold standard in the diagnosis of ALCAPA has been coronary angiography. This technique is diagnostic but comes with important risks, especially for infants with severe myocardial dysfunction, which is commonly associated with ALCAPA. Other imaging techniques can also accurately identify ALCAPA, as Cantinotti et al note in their letter. None of these techniques, however, can provide the immediate, risk-free, and accurate bedside diagnosis available with transthoracic echocardiography for this critical life-threatening disease. It has been 34 years since the initial publication describing echocardiographic identification of ALCAPA, and we believe echocardiography remains a very reliable diagnostic modality when the current technology and knowledge is applied thoughtfully and carefully.