Is there an ICRn CTC mode interrupt vector?
No, there isn't. But you do have a simple alternative: use WGM&nbsp;14
(fast PWM with TOP =&nbsp;ICR1). Then the TOV1 flag will be set after
the timer reaches TOP:

TIMSK1 |= (1 &lt;&lt; TOIE1);  // enable Timer 1 overflow interrupt

ISR(TIMER1_OVF_vect) {}  // Timer 1 overflow vector


Note that this waveform generation mode behaves very much like the CTC
mode. If you do not set any of the COM1 bits in TCCR1A, then there will
be no PWM output.



Edit: My bad. As noted by Gerben and confirmed by you, the
TIMER1_CAPT_vect can be used, and it is specified in the datasheet,
although maybe not very prominently:

In section 17.9.2 “Clear Timer on Compare Match (CTC) Mode”:


  An interrupt can be generated at each time the counter value reaches
  the TOP value by either using the OCFnA or ICFn Flag according to the
  register used to define the TOP value.


In section 17.11.40 “TIFR5 – Timer/Counter5 Interrupt Flag Register”, in
the description of bit 5 (Input Capture Flag):


  When the Input Capture Register (ICRn) is set by the WGMn3:0 to be
  used as the TOP value, the ICFn Flag is set when the counter reaches
  the TOP value.