Insert Record if no records found - SQL

I need to insert a record if no records exist. In my example below, It returned no records; therefore I need it to return the current date for the created, for CreatedBy it can be  'N/A' and Description equal to 'No Correspondence Notes'.

DECLARE @PATIENTVISITID INT = 695

SELECT
	  pc.Created
	, ISNULL ( NULLIF ( REPLACE ( pc.CreatedBy , CHAR ( 0 ) , '' ) , '' ) , 'System' ) AS CreatedBy 
	, CASE
		 WHEN pc.Description = '**long**' THEN pc.DescriptionLong
		 ELSE pc.Description
	  END AS Description
FROM PatientCorrespondence pc
WHERE pc.PatientVisitID = @PATIENTVISITID;

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